Engineering Radio – Page 64 – One Hundred percent Human Generated Content for your Reading Enjoyment

CES 2014 and the Digital Radio question

I have been busy of late, however, still keeping abreast of the news of the day. Along with that, CES 2014 wrapped up recently. No huge developments, especially when it comes to Broadcasting. However, there was one item of interest; the updated technical specifications of IEEE 802.11ac.

It is of interest here because of the implications of mobile/portable data developments and their impact on traditional AM and FM broadcasting. The new specification calls for 1.2 Gbp/s per device in the initial release, increasing that throughput to 6 Gbp/s in later releases. These data rates are for overall transmission, including the WiFi overhead. Actual usable application data (layers 5-7) would be about 20 to 30 percent less. Even so, 900 Mbp/s is a phenomenal data rate. Truly I say to you; this is the future of digital broadcasting. HD Radio™; may well prove that the “HD” stood for “Huge Distraction.”

The new 802.11ac specification uses MU-MIMO, high-density modulation, larger channel bandwidths, and beamforming technology in the 5 GHz WiFi spectrum. Of course, the question is, at what distances will this system work? If it is like conventional WiFi, then 100-200 feet is about all that can be expected. However, there are also many people interested in wireless broadband (WiMAX) service as an alternative to traditional wired ISPs. For that application, having many outdoor 802.11ac nodes connected by a backbone could potentially blanket a city or campus with free high-speed wireless data.

Along the same lines, there are many people involved in creating mesh networks of various types; be they ad-hoc mobile networks, darknets, bitclouds, etc. Mesh networking is a very interesting topic, for me at least. The network protocols are getting better and more secure. WiFi hardware is becoming less expensive and more reliable. As more and more people put effort into developing protocols like cjdns, local mesh networks will become widespread unless they are outlawed. You know; because of teh terrorism!!1!!

As it stands today, I can drive for two hours in mostly rural upstate NY and CT streaming my favorite radio programs and have nearly seamless handoffs and very few dropouts. This is on my three-year-old, beat-up 3G HTC android phone sitting in the passenger seat of my car.

Digital Radio is here, it is simply not the In Band On Channel system that legacy broadcasters have chosen.

I will read my copy, no matter what

Via youtube, the source of many unusual videos. It appears that this radio announcer will finish reading his copy, in spite of the smoke and fire:

Because being a professional is important above all other things.

Apparently, it is better to die than to look bad.

GE BT-25 Mystery transmitter site

Update: Thank you, Jim. The mystery site is KFIG (formerly KFRE) in Fresno, CA. This is what the transmitter building looks like from the outside today:

In the previously mentioned rescued file cabinet and along with the WFLY transmitter site construction information, I also found these interesting photographs:

I do not know what transmitter site this is. From the photo, it has a two-tower (guyed) directional antenna. It looks to me to be somewhere out west. The transmitter is a General Electric BTA-25 or BT-25, the same as the former WPTR and WCKY transmitter. I know this back hallway well:

Mystery AM transmitter site, back hallway of GE BT-25. Plate 9300

This is the transformer vault:

Mystery AM transmitter site, transformer vault. Plate 9297

Modulation transformer and three-pot plate transformer:

Mystery AM transmitter site, GE BT-25 modulation transformer. Plate 9299

I would say that these may be promotional photos, because of the spotlessly clean installation and the plate numbers on each print. Unfortunately, there are no pictures of the front of the transmitter, including the operator console.

Does anybody know where this is?

Satellite Dish Maintenance

Periodic attention is required for most satellite receive-only earth stations. This particular dish sticks up above the roof line of a two-story building. It acts as a big sail and sometimes, after a particular wind event, it gets slightly off of its intended satellite, AMC-8.

The real issue is doing nothing with the feed horn assembly, as it hangs way up in the air right over the edge of the roof. An extension ladder does not work, nor does a step ladder on the roof. Thus, we had to call a bucket truck to come and replace the LNB. Naturally, this work is being done on one of the coldest days of the year (so far). Temperatures at the start were 4° F or -15° C, which made the hydraulics in the bucket truck a bit reluctant to work.

When the dish was installed in 2000 or so, I swung it so the feed horn assembly was over the roof to work on it. This did not allow me to effectively check the feed horn polarization. With the bucket truck and a good satellite aiming device, I was able to find the correct polarization for the transponders in use by this station.

The old LNB was an original California Amplifiers PLL LNB from the mid 1990’s. The temperature was 35° K, which is kind of high these days. It was replaced by a Norsat C band PLL LNB with a 20° K temperature.

The satellite aiming tool used is an AI Turbo S2 by Dawn Satellite. This unit has software profiles for each satellite which can be updated over the internet. The 139° W satellite neighborhood is pretty crowded and it is easy to find yourself looking at the wrong bird. Using the aiming tool prevents that from happening, as it tells the user exactly which satellite it is receiving.

If this is a new installation, using Satellite Finder makes the rough aiming much easier.

Also, it one were interested in being very thorough, consulting the SES center of box page will give the best aiming window times. To be honest, I have never found this to make much difference.

The end result, Eb/No is 17.5 with an AG of 54. All in all, a happy satellite receiver.