There was a comment by Bob Varsha earlier in the season remarking about the audio quality of the radio transmissions from BMW compared to the other teams. It sounds very much to me like BMW uses digital radios while the other teams are on analog radios. The transmission difference is that analog gives you more buzz and hum in the background and a bit of a squelch when keying and de-keying the radio. However, considering that digital radio technology has been on the market for the better part of a decade, I have a hard time believing that to be the case. Perhaps BMW just has better noise canceling technology in their radios?

It would be really interesting to see a technology spot (RPM?) with some information about the communications technologies used in F1.

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Communications for the telemetry is probably all digital -- that's what the information is, so why change it back and forth?

As for the driver's radio, it could be either digital or analog; digital being the more likely. As for the background noise, that could be anything from noise from the engine and other electrical/electronic equipment to the ambient noise in the cockpit and the driver's helmet. It could also be a bad microphone or a dodgey connection somewhere in the communications link.

The advantage of digital technology is that it is far less susceptable to noise from radio noice caused by the spark plugs or anything else. Thus the signal remains clear until it is too weak to be heard and decyphered by the circutry. That hum you hear -- called "cross-talk" is something electrical interfering with the signal. It may be in the car, it could be somewhere else on the track (power lines, other radio signals, etc.) Or it could be in the television company's scanner.

Further, I'm presuming that each team have their own frequency (channel) assigned, so they don't all start talking on the same channel at the same time. If that's the case, BMW may just have been assigned to one that's less influenced by cross-talk and random noise.

One thing it does not appear to be is scrambled. If it were, you wouldn't be able to hear anything said at all. Or if you did, it would sound like gyberish.

Seems a few of the teams have gone digital. A couple of years ago I used frequency info from this site to listen to quite a few drivers using a standard scanner. A couple of them, McLaren & Ferrari in particular, were too distorted to understand but some were very easy to hear. In fact I had to quit listening, there was too much chatter for me to pay attention to what I was doing. Reception was pretty good from the teams, but then I was behind the wall right at pit entrance...

scrflgr - 17 September 2008 11:59 AM

Seems a few of the teams have gone digital. A couple of years ago I used frequency info from this site to listen to quite a few drivers using a standard scanner. A couple of them, McLaren & Ferrari in particular, were too distorted to understand but some were very easy to hear. In fact I had to quit listening, there was too much chatter for me to pay attention to what I was doing. Reception was pretty good from the teams, but then I was behind the wall right at pit entrance...

If they were using digital radio, you wouldn't have heard anything at all, other than possibly static -- the sort of hiss a telephone modem makes when it signs on. If you could hear voices that sounded like mush, that's scrambling, where the signal is deliberately jumbled in such a way that only a reciever with the proper de-scrambler can make sense of it.

Assuming they were transmitting on an AM (Ampere Modulation) radio like a Citizen' Band, one other possibility is that they were using single side-band radio. That type has a filter that strips the carrier frequency and the other half of the modulated signal from the out-going radio signal. You can still hear what's being said, but it sounds like adults talking in a Charlie Brown cartoon. To hear the message again, you need another circuit in the reciever that artificially replaces the carrier modulation frequencey.

Single Side Band has the advantage of allowing two different signals on the same carrier frequency, thus effectively trippling the number of channels -- Lower Side Band, AM signal, Upper Side Band.

This would not work if the signal is Frequency Modulation. There, it is the frequency that is modulated (changed up and down to make an intelligible signal), rather than the signal strength that AM uses. Thus, if an FM signal is mush, there may well be scrambling going on. Which makes sense in a high-stakes game like Formula One.