scanSydney

Discovered my 396t does not capture close call DMR signals. Put it next to a DMR radio on transmit & it stays silent.
Put it next to a NXDN radio & the frequency will be displayed with the normal data noise.
Presuming it isn't designed with that protocol.

John.

freqwaves wrote:Discovered my 396t does not capture close call DMR signals. Put it next to a DMR radio on transmit & it stays silent.
Put it next to a NXDN radio & the frequency will be displayed with the normal data noise. Presuming it isn't designed with that protocol. John.

John,

DMR uses a time slot (TDMA) rather than the 'normal' carrier when transmitting. The Close Call function of a scanner is simply not fast enough to capture the transmission. Even scanners with DMR receive capabilities cannot Close Call a DMR signal. NXDN (FDMA) simply divides a standard digital signal into two using a 'normal' carrier as opposed to a slot. When and if the GRN migrates to a Phase II P25 platform Close Call will not work with it either.

A rather simple explanation I know.

Russell

Simple, and bang on the money. The best answers are the ones that are broken into simple terms.

FDMA and any other type of "Constant Envelope" carrier with no AM component are simply seen as regular ye olde FM by close call. Close call isn't even aware that its FDMA - it just sees a constant carrier and that gives it enough time to lock on and take a stab at the frequency.

Thanks Russell for the explanation.

Regards, John.

I found that you can close call a DMR repeater though.
Probably because it transmits both slots .
Even though information might only be on one.