The popular discussion board, which was started in the mid 1990s has been terminated by it’s current owners, Streamline Digital. It seems that the site was not making any money and thus the plug was pulled.
There are other engineering type discussion boards such as The Virtual Engineer and… Hmm, Anybody?
Where a vacuum exists, nature abhors it. The question is, will anyone step up and fill the void?
One of our clients has or rather had, a BEST FERUPS 18 KVA UPS. It has stopped working and I was given the following report:
Radio guy: The power went out, the generator started, then I heard a bang.
Myself: You heard a bang?
RG: Yeah, a big BANG!
Myself: You heard a big bang.
And so he did:
Best FERUPS 18 KVA control board.
Best FE18KVA control board, MOV destruction
The primary damage is around two MOV’s mounted on the other side of the board. This is the power sense (voltage sample) input to the board. We have attempted to repair it, but alas, it is not repairable. A replacement board runs over $1,400.00 from Eaton Powerware. Since this unit also needs a new set of batteries, it is likely best to replace the entire unit.
If you have not seen this Youtube video, put down the coffee (or whatever) and move any spill able things away from the keyboard and enjoy:
As it turns out, 300 kbp/s or greater. At least in critical listening environments according to the paper titled Perceived Audio Quality of Realistic FM and DAB+ Radio Broadcasting Systems (.pdf) published by the Journal of the Audio Engineering Society. This work was done by group in Sweden and made various observations with different program material and listening subjects. Each person was given a sample of analog FM audio to listen to, then they listened to various audio selections which were using bit reduction algorithms (AKA CODEC or Compression) and graded each one. The methodology is very thorough and there is little left for subjective interpretation.
In less critical listening environments, bit rates of 160-192 kbp/s will work.
I made a chart and added HD Radio’s proprietary CODEC HDC, which is similar to, but not compatible with AAC:
||Bit Rate (kbp/s)
|HD Radio FM; HD1 channel*
||HDC (similar to AAC)
||96 – 144
|HD Radio FM; HD2 channel*
|HD Radio FM; HD3 channel*
|HD Radio AM*
||32 – 128
||MPEG II, Dolby digital
||192 – 256
||PCM, DTS, Dolby digital
||MPEG I,II,III, WMA, AAC, etc
||32-320, 128 typical
||128 – 256
||96 – 320
||64 – 256
**PCM: uncompressed data
This is the composite Mean Basic Audio Quality and 95% confidence intervals for system across all excerpts:
Over the years, we have simply become accustomed to and now accept low quality audio from mp3 files being played over cheap computer speakers or through cheap ear buds. Does this make it right? In our drive to take something good and make it better, perhaps it should be, you know: Better.
Special thanks to Trevor from Surrey Electronics Limited.
UPDATE: I notice that Radio World has a little star rating system on their articles. According to the rating, twenty one people think I suck… That is okay, but when I started looking around at all of the other articles on the website, I noticed most have but one or two votes. It seems odd to me that my little opinion piece would have so many negative votes, especially in light of the e-mails, phone calls and personal interactions I have received supporting my position.
Perhaps a few of you could run over there, read the article then objectively decide what you think… Here is the link: AM Efforts Should Include Tech Solutions
I am deeply immersed in all things networking, yet again. I regret the sparse posts, but there are a few things of note:
- It appears the the WYFR shortwave site in Okeechobee has been sold to the operators of WRMI (Radio Miami International). This is a good turn of events for shortwave broadcasting. WRMI programmed mostly to the Caribbean and were difficult to hear in these parts.
- Nielsen Radio, formerly Arbitron, says it will increase the sample size for the PPM program. This is good, larger sample size means better accuracy and fewer extrapolation related errors and strange rating spikes.
- I published an commentary in Radio World Commentary: AM Efforts Should Include Tech Solutions. What do you think? Should the industry be looking at something other than HD Radio?
- Then, from across the pond there is this:
Which is a digital radio promotion from the BBC. It seems Great Brittan is trying to force an all digital transition. A glimpse of things to come?
- In spite of the lack of posts, the blog continues to grow, averaging 550 to 600 page views per day with about 180 RSS subscribers. As far as content goes, I can assume more of the same will suffice.
As time becomes available, I will post more.
A little blast from the past. This was found in a transmitter manual at one of the sites we take care of:
CCA Optomod 8000
I thought I would scan it and make it available here. As luck would have it, there is also a corresponding piece of equipment to go along with it. I had never seen a “CCA Optomod” (.pdf) before I was working at one of the radio stations in Trenton, Florida. This unit was rescued from under a pile of garbage out in the lawn shed. It was full of mud was nests and mouse droppings. Needless to say, it required a bit of TLC to return it to operation. I replaced the electrolytics, cleaned it up and ran some audio through it. It is probably as good as the day it left the factory. Bob Orban made some really good stuff in his day.
CCA Optomod 8000
The original Optomod 8000 was an evolutionary design that made FM radio processing what it is today. The idea of combining broadband limiter, AGC and stereo generator in one box was a radical departure from the norm. The audio limiter functioned as a 15 KHz low pass filter and broadband AGC.
Orban Optomod 8000 audio limiter block diagram
The stereo generator used very modest amounts of composite clipping to reduce overshoot and transients. Many people disparage composite clippers. If done correctly, it is transparent to the listener and increases perceived loudness by stripping off modulation product that is non-productive.
Orban Optomod 8000 Stereo Generator block diagram
Some thirty five or so years later, there are still many of these units in service in various stations around the world.
PRTG network sun
As more and more broadcast facilities are moving toward IP data for all types of data transfer including digitized audio, video, telephony, documents, email, applications and programs. Managing an IP network is becoming more and more important. In most broadcast facilities, Ethernet based IP networks have been the normal operating infrastructure for email, printing, file sharing, common programs, file storage and other office functions for many years. Either directly or indirectly, most broadcast engineers have some degree of experience with networking.
With many more IP based audio consoles, routing systems, STL’s and other equipment coming online, understanding IP networking is becoming a critical skill set. Eventually, all distribution of content will transition to IP based systems and the current network of terrestrial broadcast transmitters will be switched off.
The difference between an ordinary office network and an AoIP (Audio over IP) or VoIP network is the transfer consistency. In an office network, data transfer is generally bursty; somebody moves a file or requests an HTTP page, etc. Data is transferred quickly from point A to point B, then the network goes back to its mostly quiescent state. In the AoIP environment, the data transfer is steady state and the data volume is high. That is to say, once a session is started, it is expected to say active 24/7 for the foreseeable future. In this situation, any small error or design flaw, which may not be noticed on an office network can cause great problems on an AoIP network. The absolute worst kind of problem is the intermittent failure.
Monitoring and analyzing data flow on a network can be a critical part of troubleshooting and network system administration. Data flow analysis can discover and pinpoint problems such as:
- Design flaws, infrastructure bottle necks and data choke points
- Worms, viruses and other malware
- Abusive or unauthorized use
- Quality of Service (QoS) issues
Cisco defines flow as the following:
A unidirectional stream of packets between a given source and destination—both defined by a network-layer IP address and transport-layer source and destination port numbers. Specifically, a flow is identified as the combination of the following seven key fields:
- Source IP address
- Destination IP address
- Source port number
- Destination port number
- Layer 3 protocol type
- ToS byte
- Input logical interface
Packet sniffers such as Wire Shark can do this, but there are far better and easier ways to look at data flow. Network monitoring tools such as Paessler PRTG can give great insight as to what is going on with a network. PRTG uses SNMP (Simple Network Management Protocol) on a host machine to run the server core and at least one other host to be used as a sensor. There are instruction on how to run it as a virtual machine on a windows server, which would be the proper way to implement the server, in my opinion.
For small to medium installations, the freeware version may be all that is needed. For larger network and major market installation, one of the lower cost paid versions may be required.
We or rather, I have been working on installing this CCA transmitter as a backup unit at one of our sites. It was installed as a backup at another site, but was mothballed about ten years ago. Now, we need to get it running again and re-tune it. Seems like a fairly uncomplicated job.
CCA FM-5000DS transmitter, circa 1971
Except, every time I start it, another one of these 1000 pf bypass/feed through capacitors fails. They are located at various points around the PA enclosure and route AC voltages into and out of that enclosure. The bypass function is needed to keep stray RF off of the control circuits. Normally, they have been failing with a medium resistance fault (40-70 ohms) to case. That causes the control circuit breaker to trip.
This time, however, it was on the primary for the filament transformer on the IPA tube. Just a wee little pop, followed by some ozone smell and sans power output. I have, thus far replace four of these and there are seven original still in the transmitter.
It is time to replace them all, otherwise this rig will fail when we need it the most. Replacement part is a Mouser 800-24437X5S0102MLF, 1000 pf 500 v made by Tusonix Electronics.
Not related to radio, but interesting nonetheless. Mozilla, the designer of the Firefox web browser has come up with a cool way to see tracking data for any HTTP sessions. It is an add-on called Lightbeam. I tried a little experiment, after installing lightbeam, I surfed around a little bit then looked at the results. A screenshot of the graphical output is below:
Mozilla Lightbeam graphical output
The round circles are the sites that I visited. The triangles are third party sites connected to the visited site. During the real Lightbeam session, a mouse over the icon will show the name or url. It is an interesting exercise. Visiting 27 web sites nets a total of 172 third party sites or approximately 6 third party sites per visited site. Commercial news sites like CNN and NBC seem to have the most connections to third party sites. In this case, it appears to be mostly innocuous advertizing. Even so, it is an enlightening experiment.
This is a video of Radio Sweden’s shortwave and medium wave transmitter sites:
Håkan Widenstedt at Hörby and Sölvesborgs Transmitter sites from HamSphere on Vimeo.
This was filmed in 2006. In 2010, Radio Sweden ceased broadcasting on medium and shortwave, thus I believe
these sites have Horby (HF) has been dismantled. Medium wave installation Solvesborg is visible starting at 15:30. Two tower directional array 180 degree towers with 600 KW carrier power. Quite impressive.
There is an effort to at save the Solvesborg site, perhaps as a museum.
Transmitters were in Skane, Sweden:
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h/t Shortwave Central