This was on the Wheatstone news letter a few months ago. NPR has an interesting test to see if one can hear the difference between various quality .mp3 and .wav files. There are six cuts with three versions each; a 128 kbps .mp3, a 256 kbps .mp3 and a .wav file in no particular order.
That NPR article can be found here: How Well Can You Hear Audio Quality?
I listened to all of them and found the 128 kbps .mp3 was pretty easy to pick out. On the newer material, it was sometimes difficult to tell the difference between the .wav file and the 256 kbps .mp3. Keep in mind that most radio stations stream at 64-128 kbps. Online music services like Pandora (64 kbps for free listeners, 192 kbps for subscribers), Spotify (96-160 kbps for free listeners, 320 kbps for subscribers) and Apple (256 kbps for everybody) offer slightly better quality, especially for paid subscribers.
It is too bad one cannot simulate 15 IPS analog tape. I would bet that a well mastered recording on analog tape would stand out above anything even remotely compressed.
Others have compared streaming audio to analog FM audio and found that fairly high bit rates are needed to make the quality equal: What bitrate is needed to sound like analog FM?
One more thing to keep in mind, HD Radio runs 96-144 kbps on the main channel and 20-60 kbps on the sub channels.
Two reasons for this; first, I am deep into the IP networking curriculum and time is at a premium. That being said, I am rather enjoying myself in school, which is always good. Secondly, and related to the first part, I have not been spending too much time these days doing Broadcast Engineering work. Thus, the subject matter and various topics have not been jumping out at me as they normally do.
My busy schedule not withstanding, there are some interesting things going on in the realm of Radio Engineering:
- On the LPFM front, the FCC has dismissed over 3,000 translator applications from the great translator invasion of 2003. This is great news and now potential LPFM applicants can use the FCC LPFM search tool to get a good idea of what is available in their neck of the woods. Other search tools include Recnet and Prometheus Radio project. Filing window is October 15, 2013, apply now or forever hold your peace.
- Chris Imlay has some good ideas on AM revitalization. His suggestion is to have the FCC enforce and strengthen its existing rules regarding electrical interference. I notice two letters are missing from his list, those would be “h” and “d.” While the ideas are technically sound, it seems unlikely that the FCC can or would be able to enforce stricter Part 18 rules.
- Lots of EAS shenanigans going on with zombie alerts and hijacked EAS systems. Really people, default passwords? Secure your equipment and networks or pay the price for complacency. Nearly all new equipment has some sort of web interface, which can be a great time saver. They can also be easily exploited if left vulnerable. Fortunately, this was not as bad as it could have been.
- Something happened in NYC that hasn’t happened in quite a while. Country music filled the air on a station that is generally receivable in the five boroughs. This may not seem like big news to the rest of the country, but in market number one, it is big news. Further, Cumulus has registered “NashFMxxxx.com” for every FM dial position. National country channel in the works? I’d bet yes. A look at recent trends shows that Cumulus is standardizing formats on many of its AM and FM stations, making them, effectively, part of a nation network of over the air repeaters.
- Clear Channel has put more effort into iHeartradio, for seemly many of the same reasons as Cumulus’s standardized formats.
Where is this all going? There are several trends evident including; AM will eventually be declared DOA and switched off, transition to national based music formats, an emphasis on IP (internet) based delivery systems, an eventual phase out of local programming, smaller staffs concentrated on local sales and little else.
The single bright spot could be LPFM. Only time will tell if this new crop of LPFM licensees will keep the faith and tradition of local radio. If one looks at the natural course of evolution, under times of extreme stress, species tend to get physically smaller in response. The larger species cannot sustain themselves with the necessary energy intake and die off. See also: Dinosaurs. I certainly would call this prolonged, nearly dead economy stressful on the broadcasting business. Perhaps, when all is said and done, it will be the small, volunteer LPFM still on the air and serving the community.
FM and AM broadcast radio processing has gone through many iterations. At first, the main processing function was to limit the input audio to a transmitter and prevent over modulation. This was a particular problem with early tube type AM transmitters, where over modulation could create power supply overloads and kill the carrier while engineers scrambled around resetting things and hopefully pressing various buttons to get the transmitter back on the air.
Over the years, processors incorporated not just limiting, but compression, gating, equalization, clipping and so on all in an effort to keep ahead or at least abreast of the station across town.
Today, broadcast air chain processors come in all shapes and flavors. In addition to that, internet streaming stations have their own unique set of issues to deal with. The top of the line Telos Omina or Orban Optomod systems are great, however, they can set one back a pretty large sum of money. Enter then, the Stereo Tool PC based software processing program.
Stereo Tool sofware screen shot
The first difference between, say the Omina and Stereo Tool is the end user decides the hardware and basic operating system. The second difference is Stereo Tool comes with a free trial. Then there is the price difference, which ranges from about $48.00 US for the basic version, to $161.00 US for the basic FM version and finally $269.00 US for the full version (actual prices are in Euros, which will fluctuate day to day and the credit card company will likely charge an exchange fee). Add to that a medium speed (2 Ghz) Intel Pentium4 or better computer, 1 Gb or more of RAM, good sound card and it all comes out to a reasonably priced audio processor.
Here are some of the specific features for broadcasting:
- Hiss Removal Filter
- FM Hiss Removal Filter
- Automatic Gain Control (AGC)
- 10-band multiband compressor / limiter / clipper
- Phasing error (AZIMUTH) correction filter
- Stereo booster
- Bass booster
- Final limiter
- Distortion masking Loudness filter
- Lowpass filter
- FM pre-emphasis filter
- FM stereo encoder
- FM RDS encoder
- Composite limiter
Much more info at the Stereo Tool website.
The idea of PC based audio processing is new and interesting to most of us. The designer and owner of Stereo Tool, Hans van Zutphen, was nice enough to answer a few questions I posed to him via email:
PT: What prompted you to write audio processing software?
HvZ: Since I was very little I’ve always wanted to have my own radio station. I remember playing with walkie-talkies and trying to receive their sound on a real radio when I was about 8 or 9. I never really did anything with it until I found out in 2001 that you could easily start a webradio station – I actually found out because I was listening to a pirate station in my car which turned out to have a stream; within a week my own station was online.
Of course I needed a bit of processing for it, and I wrote some command line tools – a singleband compressor, a stereo to mono convertor that didn’t cause any loss of audio (I was broadcasting hard trance on a mono 56 kbit/s stream, and this was the only way to get a decent sound out of it), and some time later a multiband compressor.
In 2004 I left the company I worked for (ASML, they make machines to make computer chips, customers are companies like Intel, AMD etc.) to start working for Philips Healthcare, where I was going to work on image processing for X-Ray systems. I had 2 months of ‘spare time’ between those jobs, and I wanted to learn to program in Visual C++, so I decided to a GUI around my command line tools, and make a Winamp plugin out of it. I called it ‘Radio Tool’. I never really planned to do anything with it, it was just an exercise project.
About a year later I came across the Winamp site again and I saw that you could upload plugins. So I uploaded my program, now renamed to ‘Stereo Tool’ because a Google search for “Radio Tool” gave far too many hits. Within a week there were over 1000 downloads and a while later it surpassed 90,000. At that point I decided to create a new version, Stereo Tool 2.0.
For quite a while this remained a hobby project, I occasionally worked on it for a few months and then I wouldn’t look at it for months. But at some point I was approached by someone people who worked at a “real” (FM) Dutch radio stations who asked for some extra features – he couldn’t get the audio loud enough, and that’s how I got into clipping. Things started to get better, I learned more and more about processing, the number of downloads increased and people became more and more enthusiastic about it. At some point, after reading something about how an FM stereo signal looks, I thought it might be possible to output a stereo signal with a 192 kHz sound card, so I bought one and did some tests and it worked that same night, and within a few weeks I added RDS.
PT: Do you know, approximately, how many stations (AM/FM/internet) Stereo Tool is being used on?
HvZ: FM: About 500, ranging from small community and pirate stations up to large nation-wide stations which run Stereo Tool at a dozen transmitter sites. Streaming: Not sure, but definitely over 1,000, probably a lot more.
PT: I have read through the forums on your site, Stereo Tool looks like a very complete processing system. Any plans for new features, future upgrades, etc?
HvZ: Yes. I’m currently working on a new multiband compressor. The multiband compressor in Stereo Tool is still based on the code that I wrote in 2001 for my webradio station, which in turn was based on an even older version that I had used on 8-bit audio. It also has far too many bands. Because of this, the multiband compressor is currently the weak spot of Stereo Tool. In the last weeks I have made a new singleband compressor that sound a lot better, it actually outperforms other compressors I have tested, and I expect great results for the new multiband compressor, which will also have less bands. Something else that I’ve been planning for a long time is a composite clipper, which will add 1-2 dB of extra loudness and especially better highs. Stereo Tool can already be louder with good audio quality than nearly any hardware box on the market (see for example this video, Radio 538 uses an Orban 8600 http://www.youtube.com/watch?v=4VpfcqUPQys – unfortunately due to the mpeg compression it’s a bit difficult to compare but listen for distortion ) – but there’s always room for improvement.
PT: What are the advantages of a PC software based processor vs. a hardware based (e.g. Omni or Optomod)?
HvZ: Ah, good question. Not sure if it’s the right question… With processing, a lot of things come down to taste, and there are several stations that have replaced their hardware processing by Stereo Tool not because it’s software and PC based but because they preferred the audio that comes out of it. Stereo Tool is also one of only 2 processors that contain a declipper (the other one is the Omnia 9, I licensed my declipper to them). For a demo of the declipper see: http://www.youtube.com/watch?v=oqOljvx9KaM
Also, Stereo Tool contains a stereo and RDS coder, most other processors don’t, so instead of having a whole bunch of devices everything can be done in a single PC, which also results in a better quality. Recently I added a new feature that enables synchronizing multiple FM transmitter signals that all connect to a simple Shoutcast stream (video: http://www.youtube.com/watch?v=GYQ5CYs0ZX8 ), so you also don’t need any streaming hardware anymore.
Of course there’s the price. A hardware box that gives “similar” quality (of course every processor sounds different, and it’s a matter of taste, so it’s difficult to compare, but I’m assuming that things like low volume levels, gain riding, distortion and lack of clarity in the highs are bad) easily costs $10,000 or more. And you can always easily upgrade to new versions. If you already have a PC with enough spare processing power you don’t need to buy anything.
I know that some people at radio stations are ‘afraid’ of using a PC in their processing path, but based on feedback I get from the stations that run my software it’s completely stable – and of course if a PC does break, you can replace it with any fast enough PC you have lying around – you just need to put the proper sound card in.
But for development, the advantages are huge. If you use DSP’s, it’s usually a lot of work to even make a very small change. When I worked at Philips Healthcare, the image processing that had been done – without much changes – on DSP’s for many years was being converted to PC’s because of speed of development and price of hardware. Once the conversion was finished, the development speed increased dramatically and 2 years later the image quality had improved beyond anything that was imaginable with DSP’s. PC’s get faster every year, and you don’t have to do anything for that – for the same price the processing power that you can buy roughly doubles every 1.5 years, and if you pay more you can get even more. If you use DSP’s, you have to do a lot of work yourself, you cannot just ‘buy a faster DSP’. Testing things is very easy, I can write some code that does something new, post it on my forum and I’ll have feedback from users the next morning – with DSP’s that’s a LOT more difficult and it takes a lot more time. I’ve learned by now that everyone hears things in a different way, and occasionally there are groups of people who hear something they find very annoying while many other people (often including myself) don’t hear anything wrong with it at all. Especially in cases like this it’s really great to be able to quickly send new versions to several people all around the world for testing.
PT: Are there any particular sound cards that work better with Stereo Tool?
HvZ: Yes. For the best results, use the Marian Trace Alpha, with the ESI Juli@ as second-best choice (it needs calibration).
Thank you very much, Hans, for the interesting insight.
Checkout the videos, especially the declipper video, which is quite amazing. That will cleanup all but the most ham handed DJ mistakes.
PC based audio processing software is a great solution stations on a limited budget that cannot afford high end air chain processors. There are many LPFM’s, Part 15 stations and others that can get great sounding audio and RDS for a very reasonable price. Currently, the AM settings do not allow asymmetrical modulation, which is more of a US thing. There is some talk of adding it in a later update.
Wireless IP Ethernet (802.11) technology has been around for a while. Many know it as “WIFI” but you could also call it “WLAN” or something similar. Like many other Ethernet technologies, WLAN relies on a spoke and hub connection system. The hub being the wireless access point or router and the individual hosts (PC’s, tables, phones, etc) being the end point for each connection. In a wired network, it is usually some type of switch that forms the center of the network data distribution system.
With a wireless mesh network or ad hoc network (802.11s), each wireless device can connect to any other wireless device within range. In this type of peer to peer network, there is no central access point, although something can act as an internet gateway or there can be several gateways. This type of topology functions much like the public network (AKA the internet), where there are many different paths to any one (major) destination. If any one of those paths goes down, another route is quickly found.
This technology was developed by several vendors for military communications systems and for OLPC (One Laptop Per Child) programs in Africa and other places. Each link acts to extend the boundaries of the network, thus the more users there are, the more useful the network becomes.
Wireless Mesh Network diagram
Advantages of mesh networking:
- Networks are self forming; once the nodes are configured and can see other network nodes, the the network automatically forms
- Networks are self healing; if one node drops off line, traffic is automatically routed to other nodes. If the node comes back up, it is included back into the network
- High fault tolerance; in areas where many nodes exist and can see each other, the failure of any single node does not effect the rest of the network
- Low cost to deploy; mesh networks use standard off the shelf WLAN (802.11) devices. Choice of software will dictate which hardware will work the best
- Crowd sourced infrastructure; as each network node is owned by an individual, the cost and responsibility is shared among the community
Several specific routing protocols have been developed for the network side of the system. Hazy Sighted Link State Routing Protocol (HSLS), BATMAN, OLSR HWMP and others. These work well with the existing 802.11 a/b/g wireless network hardware currently available.
On the host side, a good IBSS capable wireless network adapter is needed, which many of the newer ones are. Several of the software programs have lists of WLAN adapters that work with their software. Open Garden is a free App for Windows, Mac OSX, Android, and they are working on an iOS version. This leaves out certain devices like tablets and iPhones for now.
Since existing wireless adapter drivers do not yet support mesh networking, usually an additional piece of software is needed. There are several interesting ones, including HSMM-MESH, which was developed by Amateur Radio operators. Open source programs for Linux, Free BSD and other are available as well as commercial versions for Windows.
I was thinking that this might be useful for broadcast applications. For obvious reasons, this type of system would work best in densely populated urban and suburban areas, which is exactly the type of area that LPFM licenses might be hard to come by. For those who do not have the time or wherewithal to apply for an LPFM license, or for those that simply don’t get a license due to scarcity of available channels, this could be a great way to cover a neighborhood or section of a city. The more people that participate in the mesh network, the stronger the network becomes. Additionally, by using FCC type accepted part 15 FM and AM transmitters as broadcast nodes, carrier current transmitters and leaky coax systems, the presence of the mesh network can be advertized to potential listeners, including directions on how to take part.
Wireless mesh network example, courtesy of Meraka Institute
Wireless LAN bridges or broadband internet connections can act as a backbone between distant nodes.
For bandwidth efficiency sake, AOIP services should be limited to multicast addresses.
A good site with more wireless mesh network information is http://wirelessafrica.meraka.org.za/
Two sub-reddits on the subject: /r/meshnet and /r/darknetplan
Then there is project meshnet and the project meshnet wiki
Oh, by the way, go ahead and ask me what I have been learning about in school these days…
I have been watching the LPFM proceedings with some interest. The FCC has not exactly promised to have a filing window by end of 2012, but indicates that it might try to do that. In comparison to such evolutions in the past, this is moving pretty fast. Those that want an LPFM station need to start planing now. As in previous LPFM windows, the availability is for non-profit organizations only. This does not mean all hope is lost; NPR stations are all non-profits and most of them are very successful.
One of the biggest questions is: How much will it cost? Like all things, it varies greatly. If I were to put an LPFM or internet radio station on the air, there would be certain minimums, such as the use of professional audio equipment, a new antenna, and some type of redundancy.
Generally speaking, radio stations and internet stations both need some type of office/studio space. This can range from large and opulent to a closet. The costs for these would depend on the type and quantity of equipment installed, whether the equipment is new or used, the building, the area, etc. Those facilities also have monthly reoccurring costs such as rent, electric, telephone service, internet service, etc.
Since internet radio stations and traditional terrestrial over the air radio would use the same type of studio equipment, those costs will be similar. Here is a breakdown of the studio equipment:
||Cost new (USD)
||Cost used (USD)
|12 Channel professional audio console
||Analog, 4 buss, telephone mix minus
||Can also be fabricated locally
|Microphones, RE-20 or SM-7B
||Per unit, several required
||Can also use consumer version
||Can also use consumer version
||Professional unit with balanced outs
|Computer w/ professional sound card
||For automation and sound file storage
|Computer, general use
||General information web browsing
|Computer, Streaming w/sound card
||Sound card should be good quality
|Studio Telephone system
||Used for call in/on air
|Barix remote box
||Used for IP remote broadcasts
|Comrex Matrix POTS codec
||Used for telephone line remote broadcasts
|Misc wiring, hardware, ect
||Connectors, mic booms, wire, etc
Some equipment is not available used such as Barix boxes. Of course, not all of this is required for a radio station, however, most local radio stations would want the capability to do remote broadcasts, take phone callers on the air, have multiple guests in the studio, etc.
For a traditional LPFM station, the transmitting equipment would entail:
||Cost New (USD)
||Cost Used (USD)
|300 watt transmitter and exciter
||Smaller transmitters with higher gain antennas can also be used
|2 Bay ½ wave spaced antenna
|125 feet ½ inch coax
|100 foot guyed tower and installation
||Not needed if station is on tall building or leased site
|STL; IP radio w/ barix boxes
||In lieu of standard 950 MHz STL
|STL standard 950 MHZ
|| Used in lieu of IP STL
|STL antennas, transmission line
||Can also use software such as Breakaway Broadcast
|Misc connectors, grounding kits, etc
||Fully operational CAP compliant
|Processing software, Breakway broadcast
||In lieu of standard FM processor
This is a generic station, most will be somewhat different due to antenna supporting structures, transmitter powers and antenna types. For the best possible signal, a circularly polarized antenna should be used. A two bay, 1/2 wave spaced antenna will give the maximum signal density, while minimizing downward and upward radiation. The upward radiation is simply wasted energy, as no one in space is listening to FM radio. The downward radiation reduction is key if located in congested areas.
For internet radio station, the following would be required:
||Cost New IUSD)
||Cost Used (USD)
||Includes professional sound card
|Audio processing software
||Recommend software such as Breakaway Broadcast
|Audio Processing, outboard hardware
||In lieu of software
|Audio Streaming aggregator
|| 1,200 to 2,400
While LPFM’s are much more expensive than internet only stations, LPFM’s have the advantage of built in marketing, which is the on air signal. If it is broadcasting on the air, word will get out. On the internet, some other type of marketing will be needed to spread the word. Also, LPFM’s should also be streaming, which would incur the same costs above.
The long and short of it is, to put a technically viable LPFM on the air is not an inexpensive proposition. It is worth the effort, however, because the advantages of an LPFM over an internet only station are great.
Rack Mounted servers in data center
As Google can verify. According to the NYT piece: Google Details Electricity Usage, Google said its operations draw approximately 260 million watts continuously to run their online services and office buildings. That figure includes all of the e-mail applications, Youtube videos, Google searches, Google documents, etc. That works out to be about 6.24 million KWh per day or 21,292,752,000 BTU per day. Here are some of the amounts and costs for other fuels:
||Average cost $
||Cost per day
Those figures do not take into account the efficiency of the generation process. For example, the average coal fired power plant is 32% efficient, thus the actual tonnage of coal needed to produce 6.24 million KWh is 1,376 at a cost of $215,194. Other fuels have similar electrical conversion efficiency, with the internal combustion engine being about 19% efficiency for any given fuel.
Some other interesting tidbits from the article:
- Each Google search uses about 0.3 Watt-hours of electric
- The average user uses 180 Watt-hours per month
- Approximately 12.5 million Watts or 30,000 KWh per day are used by search engine traffic
- 25% of Google’s energy is supplied from renewables
- Google designs and builds it’s own data centers using energy efficient technology
One can assume that other data centers are not as efficient as Google’s. It would be interesting to do a comparison between the electrical use by AM and FM broadcast transmitter sites and the energy used by data centers that stream radio content. Right now the data center’s electrical costs are still relatively low because over the air radio listenership far out strips on line listenership. Eventually, those numbers will flip and I’d think the increased costs associated with greater streaming will be paid by somebody, likely the content generator.
All those webstreams, videos, search engine queries are not free.
Several places have reported that The Voice of America will sunset it’s shortwave broadcasts in the not too distant future. Boing Boing reported yesterday, based on a paper titled “Broadcast Board of Governors 2010-2012 BBG Technology Strategic Plan and BBG Technology Update – 2009” received via FOIA last January.
The 2009 study notes that the weekly audience for radio is 101.9 million listeners, TV is 81.5 million and the Internet 2.4 million weekly listeners. I don’t know how much that has changed in the last two years, but I’d imagine some shift towards the internet has taken place in light of recent shortwave transmitter site closings.
There are several interesting aspects of this report, notably the disparity between what is termed “Classic Engineering” and “Classic IT” fields. This is the concept that radio engineers toil on RF and transmitters, while the IT guys work with computers.
As the dependence on shortwave continues to wane and the distribution focus shifts to third party operations, satellite and other direct-to-consumer methodologies, the skill sets of some engineering personnel become less and less relevant to the agency.
This issue is further compounded by the relatively difficult transition from a traditional RF, antenna, transmitter design, and maintenance knowledge base to the technologies involved in digital satellite and IP-based networking systems.
Perhaps that is how it is done in government circles, but I have found in private sector, most radio engineers know at least the computer automation systems that run the stations. Of course, everyone has preferences and we tend to gravitate toward things we like to do, especially in a field as diverse as broadcast engineering. When I was in the military, somebody posted the “Eleven Rules of Success.” The only one that I can remember now is this: “Pick the thing that you hate and become proficient at it.”
In order to stay relevant, broadcast engineers have to keep up with the technology while remaining proficient with RF and audio skills. Computers and automation programs are not terribly hard to understand, but each one is different and operates differently. Most, if not all automation companies offer some type of training, which is fine. Nothing can beat hands on installation and trouble shooting for learning the important details, however.
The report also mentions that morale is an issue for several reasons. First, it is noted that:
Despite several recent high profile station closings, the organization continues to employ shortwave as the most important transmission mechanism to many of the target areas around the globe. Often surge activities are enabled byvadditional shortwave transmissions that end up as an integral part of the ongoing schedule. Effectively, this diminution of transmission resources accompanied by no reduction or even an increase of reliance on this transmission methodology creates overburdened schedules and often the deployment of less than optimal assets for transmission into target areas.
This additional operational burden likely extends to other disciplines within the agency where programming staff must expend substantial additional effort to produce or adapt content for a multiplicity of transmission methods.
In essence, the decision process for station closing does not appear to follow an overt decision and stated plan to reduce shortwave usage.
That is known as the “more with less” paradox. In the private sector, more with less has been going great guns since the first loosening of the FCC’s ownership rules in 1994. For those that are used to working in optimum conditions, anything less is a shock to the system.
The issue of low morale is palpable and often present in conversations that address historical perspectives on a particular station closing, transfer of technologies around the network and any other such topics. Precipitated by the long periods of employment that are relatively standard in the Engineering area and perfectly understandable, this grieving process is a natural consequence of the pride involved in creating a state-of-the-art technical facility only to see it being dissected piece by piece as technology continues its relentless creative destruction.
An interesting statement and it shines a light on several things heretofore unsaid in broadcast engineering. We love our transmitters, as strange as that may seem. We love our towers and antennas. Parting with something that has become an integral part of our working environment is difficult to say the least. Watching something be signed off for the last time and then hauled to the scrap heap is very disheartening, especially if there is no replacement.
On the IT side, things are not so good either. The main concern is the infrastructure of the IT backbone. Several deficiencies are noted in the cabling and router; the cabling is in serious disarray and there is only one router for the facility. There is also other problems noted with personnel and lack of project management experience and/or IT department goals.
Overall, moving into new media fields makes sense. There are, however, many places where new media is unknown or at best, mostly unavailable. Moving content delivery from over the air broadcast to IP based distribution may be far less expensive to operate, that is true. It is also far more susceptible to being disrupted by accident or design. In those areas where the internet is spotty, shortwave radios are abundant and relied upon. If the VOA is not on the air, then some other station will be.
I have had my HTC Android phone for just about a year now, which is enough time to learn the device’s strengths and weaknesses. I have done a fair amount of listening to audio, watching youtube videos and playing .mp3’s to give me some idea of the technical quality and operational issues. Like anything else, these are general observations. Some radio station’s streams sound better than other due to the effort those stations put into audio quality.
The listening test was done with a set of Sony earbuds, which sound far better than the small speaker built into the phone. For ease in streaming audio, I used the TuneIn Radio application for Android by TuneIn Inc. For this test, I only listened to FM broadcast stations, both streaming and over the air.
The over the air tuner is the stock factory radio in my 1997 Jeep Cherokee. I would rate the radio average in every way. The actual tests were done driving around on interstate highways and other major roadways. There were a few instances where I had to give up on the Android phone due to traffic and driving considerations.
My Android phone has an FM tuner installed in it, however, it is really useless. I get only local stations, and then their audio is all hissy and for the most part unlistenable. The HTC FM tuner uses the headphone wire for an antenna, which may be a part of the problem.
Here is a chart of my observations:
||Analog FM radio
||Streaming via Android
|Overall Station Selection
||Only those stations that can be received
||Any station that is listed in TuneIn Radio App*
|Varity of interesting programming
||Only those receivable signals which limits it to a few well programmed stations, the rest being garbage
||Almost unlimited, world wide*
||Only those stations that can be received
||Any station that is listed in TuneIn Radio App*
|Ease of use
||Can press the preset or scan buttons on radio without taking eyes off the road*
||Requires squinting at a small screen and pressing several little boxes to get to the desired station
|Annoying commercial avoidance
||See above on preset and scan buttons*
||Very difficult to change stations quickly
|Quality of sound
||Good to excellent, depending on the station’s signal strength*
||Fair to good, depending on the bit rate and network congestion, some stations sound very good and some can sound very bad
||Occasional picket fencing with distant stations, otherwise, non-existent*
||Varies depending on location, can be quite annoying, especially in mobile environment. App also occasionally locks up and needs to be restarted
||Free, radio came with the vehicle, no paid data service needed*
||Requires data plan with smart phone, some plans cap data amounts, can be fairly expensive
I am having a difficult time assigning the overall enjoyment as well as an over all winner. One the one hand, it was very cool, driving down I-84 in Danbury, CT listening to Howlin’ Wolf on New Orleans’ non-commercial Jazz station, WWOZ. On the other hand, it was a right pain in the ass to get to that point, in rush hour traffic. By the way WWOZ’s web stream is excellent, audio wise.
From a safety and ease of use, the FM radio in the Jeep wins hands down, I just don’t know how many more times I can listen to the same Led Zeppelin song on i95 (that used to be I-95, frankly I thought Steve Jobs copyrighted the lower case i).
The drop outs were also a concern, mostly taking place in on the section of I-84 going through Putnam County, NY. I don’t know if my cell carrier needs to beef up it’s data coverage in that area, or if there were just a great many users on the network checking their e-mail, etc.
If they could sort out the ease of operation problem and get rid of the drop outs, streaming audio over HTC Android would win hands down.
Computer audio sound cards are the norm at nearly all radio stations. I often wonder, am I using the best audio quality sound card? There are some trade offs on the quality vs. cost curve. At the expensive end of the curve, one can spend a lot of money for an excellent sound card. The question is, is it worth it? The laws of diminishing returns states: No. High quality reproduction audio can be obtained for a reasonable price. The one possible exception to that rule would be production studios, especially where music mix downs occur.
I would establish the basic requirement for a professional sound card is balanced audio in and out, either analog, digital or preferably, both. Almost all sound cards work on PCI buss architecture, some are available with PCMCIA (laptop) or USB. For permanent installations, an internal PCI buss card is preferred.
Keeping an apples:apples comparison, this comparison it limited to PCI buss, stereo input/output, analog and digital balanced audio units for general use. Manufactures of these cards often have other units with a higher number of input/output combinations if that is desired. There are several cards to choose from:
The first and preferred general all around sound card that I use is the Digigram VX222HR series. This is a mid price range PCI card, running about $525.00 per copy.
Digigram VX222HR professional sound card
These are the cards preferred by BE Audiovault, ENCO and others. I have found them to be easy to install with copious documentation and driver downloads available on line. The VX series cards are available in 2, 4, 8, or 12 input/output configurations. The HR suffix stands for “High Resolution,” which indicates 192 KHz sample rate. This card is capable of generating baseband composite audio, including RDS and subcarriers, with a program like Breakaway Broadcast.
- 2/2 balanced analog and digital AES/EBU I/Os
- Comprehensive set of drivers: driver for the Digigram SDK, as well as low-latency WDM DirectSound, ASIO, and Wave drivers
- 32-bit/66 MHz PCI Master mode, PCI and PCI-X compatible interface
- 24-bit/192 kHz converters
- LTC input and inter-board Sync
- Windows 2003 server, 2008 server, Seven, Eight, Vista, XP (32 and 64 bit), ALSA (Linux)
- Hardware SRC on AES input and separate AES sync input (available on special request)
Next is the Lynx L22-PCI. This card comes with a rudimentary 16 channel mixer program. I have found them to be durable and slightly more flexible than the Digigram cards. They run about $670.00 each. Again, capable of 192 KHz sample rate on the analog input/outputs. Like Digigram, Lynx has several other sound cards with multiple input/outputs which are appropriate for broadcast applications.
Lynx L22-PCI professional sound card
- 200kHz sample rate / 100kHz analog bandwidth (Supported with all drivers)
- Two 24-bit balanced analog inputs and outputs
- +4dBu or -10dBV line levels selectable per channel pair
- 24-bit AES3 or S/PDIF I/O with full status and subcode support
- Sample rate conversion on digital input
- Non-audio digital I/O support for Dolby Digital® and HDCD
- 32-channel / 32-bit digital mixer with 16 sub outputs
- Multiple dither algorithms per channel
- Word, 256 Word, 13.5MHz or 27MHz clock sync
- Extremely low-jitter tunable sample clock generator
- Dedicated clock frequency diagnostic hardware
- Multiple-board audio data routing and sync
- Two LStream™ ports support 8 additional I/O channels each
- Compatible with LStream modules for ADAT and AES/EBU standards
- Zero-wait state, 16-channel, scatter-gather DMA engine
- Windows 2000/XP/XPx64/Seven/Eight/Vista/Vistax64: MME, ASIO 2.0, WDM, DirectSound, Direct Kernel Streaming and GSIF
- Macintosh OSX: CoreAudio (10.4)
- Linux, FreeBSD: OSS
- RoHS Compliant
- Optional LStream Expansion Module LS-ADAT: provides sixteen-channel 24-bit ADAT optical I/O (Internal)
- Optional LStream Expansion Module LS-AES: provides eight-channel 24-bit/96kHz AES/EBU or S/PDIF digital I/O (Internal)
Audio Science makes several different sound cards, which are used in BSI and others in automation systems. These cards run about $675 each.
Audio Science ASI 5020 professional sound card
- 6 stereo streams of playback into 2 stereo outputs
- 4 stereo streams of record from 2 stereo inputs
- PCM format with sample rates to 192kHz
- Balanced stereo analog I/O with levels to +24dBu
- 24bit ADC and DAC with 110dB DNR and 0.0015% THD+N
- SoundGuard™ transient voltage suppression on all I/O
- Short length PCI format (6.6 inches/168mm)
- Up to 4 cards in one system
- Windows 2000, XP and Linux software drivers available.
There are several other cards and card manufactures which do not use balanced audio. These cards can be used with caution, but it is not recommended in high RF environments like transmitter sites or studios located at transmitter sites. Appropriate measures for converting audio from balanced to unbalanced must be observed.
Further, there are many ethersound systems coming into the product pipeline which convert audio directly to TCP/IP for routing over an ethernet 802.x based network. These systems are coming down in price and are being looked at more favorably by broadcast groups. This is the future of broadcast audio.
I am a strong proponent of non-computer based air chain processors. Something about listening to dead air while the computer reboots is annoying and every computer needs to be rebooted every now and again.
All of that being said, I recently had a chance to play around with Breakaway Broadcast audio processing software. I have to say, as a low cost, very versatile platform, it can not be beat. I would put it up against any of the high end FM audio processing, provided one uses a high quality sound card with an adequate sample rate.
Claesson Edwards Audio has developed several software based audio processors for a variety of end uses. They make several recommendations for hardware and operating systems, Pentium 4 3.2 GHz or better, dual core preferred. If one is interested in used the sound card to generate composite audio, then any sound card capable of true 192 KHz sample rate will work. They list several that have been successfully tested on their web site.
For approximately $1,200 dollars or so, one could buy a decent computer, the Breakaway Broadcast software and the Airomate RDS generator software. For a Mom and Pop, LP or community radio station that is looking to do some high end audio processing and or RDS, that is a good deal. I would add a UPS to the computer and keep back up copies of the software installed on an emergency computer just in case. One can never be too safe when it comes to computers, viruses, hackers and other malicious persons.
Things that I like
- Inexpensive, the fully licensed version is $200.00. The demo version is free but there is a 30 second promo every thirty minutes.
- There are several factory presets, but everything is fully configurable, changes can be named and saved allowing some experimentation.
- Audio cards with 192 KHz sample rate or greater can be used to generate composite audio, eliminating the need for a separate stereo generator
- RDS capable with additional software (Airomate2, approximate cost $35.00)
- The same processing computer can be used for streaming audio and or AM audio processing simultaneously.
- Full set of audio calibration tools for AM and FM transmitters, allows correction for tilt, overshoot and linerity. Can add pre-emphasis at any user selectable rate.
- Fully adjustable phase rotators.
Things that I don’t generally like:
- Computer based system using Windoze operating system
WXPK in White Plains, NY has been using this software to process their streaming audio for about 2 years now. The software itself is extremely stable running on a stand alone Windows box with XP service pack 2.