PT Wireless Transmission Frequency

RapDaddyo

Does anybody know what frequency the PT hubs transmit on? The specs just say, "Digital RF" and the Saris support rep didn't know. I want to anticipate and avoid interference with other wireless devices and it would be helpful to know the frequency or frequency range of the PT hubs.

F1_Fan

Can't tell you the frequency but maybe these observations help:

Currently on my bike I have (this is a lot because I just got the SL and haven't removed the redundant devices yet) the following transmitters: Vetta cadence, Vetta speed, Polar speed, PT SL. The speed sensors are on the fork and the cadence sensor on the chainstay.

My bike has the following receivers: Polar 710i, Vetta 100A, PT SL

The only interference among all of those devices is that the Polar speed sensor (but not the Vetta one) is picked up by the PT head unit as heart rate. That means I can't run the Polar speed sensor at the same time as the PT is recording HR. Everything else is fine though. It's a shame the Polar and the PT don't work completely together because the Poalr coded HR belt actually works with both devices...

frenchyge

Really? I can pick up the uncoded PT chest strap on my Polar watch, but I can't pick up the coded Polar chest strap on my PT receiver.

RapDaddyo

Update: Saris responded to my query to say that the hub transmits at 8 kHz and the HR strap transmists at 5.0-5.2 kHz. Does anybody know of a cheap device I can use to test this -- a frequency scanner that picks up digital RF transmissions in this frequency range?

frenchyge

That's a surprisingly (to me anyway) low frequency. Heck, you could see that on a spectrum analyzer built into a home stereo if you had a tuner that could receive a signal frequency that low. The problem with frequencies that low is that it typically takes a *large* antenna to receive them. I'll poke around a bit to see what I find, but you might ask Saris if that's the data frequency or the *carrier* frequency. The carrier frequency is what would be of concern to you for interference considerations, and I would expect it to be in the Mhz range at least.

F1_Fan

It's the reverse for me... I verified it. Odd.

F1_Fan

I can hear it as an audible click in my headphones sometimes so I think that means it's in the audible range of 20Hz-20KHz (unless I'm hearing a harmonic).