Voice on CH70

[chris123]

Originally Posted by HDAV

Guess the programming is done in bulk, shame it doesn’t have M1 or M2 programmed, European spec set I think.

M1 (157.850 MHz) may be programmed as channel 37 (or channel 37A), M2 (161.425 MHz) may be programmed as P1 or P4 - worth checking if your VHF has any of these.

[simonl]

Originally Posted by ShinyShoe

Its simplex. No legacy. Just straightforward simplex. No half duplex.


I may be wrong - but the data burst is TINY - I doubt you'll audibly hear it. Its transmitted at 1200Baud and there isn't that much data to transmit

Given that all stations transmit to each other on a peer-to-peer basis I'd call that half-duplex.

[ShinyShoe]

Originally Posted by simonl

Given that all stations transmit to each other on a peer-to-peer basis I'd call that half-duplex.

I'd call it simplex, the International Telecomunications Union agree with me. Two stations in communication send an receive on the same frequency. So only 1 can send or receive at one time.

Duplex - both stations send and receive on opposite frequencies. Like CH80. On CH80 on your boat you can hear all the marinas who are on the 'opposite' frequencies and they can hear you. But another boat on 80 can not hear you (without tweaking their programming). In theory CH80 could be full duplex - you can talk while the other end also talks. BUT in ITU's definitions your kit is only half duplex - so you can't receive while transmitting.

[HDAV]

Originally Posted by chris123

M1 (157.850 MHz) may be programmed as channel 37 (or channel 37A), M2 (161.425 MHz) may be programmed as P1 or P4 - worth checking if your VHF has any of these.

No it doesn’t, isn’t a big issue it’s only a spare used for testing the main one or occasional use. I think it’s euro spec and not worth programming I can buy a brand new one for under £100

[Iron Dials]

HDAV my SH fixed vhf didn't have M1 or M2 when I installed it.
Apparently there should have been a "yellow sheet" in the box telling what combination of buttons to push.
I contacted Standard Horizon directly by email and they gave me the sequence to "localise"it.

[simonl]

Originally Posted by ShinyShoe

I may be wrong - but the data burst is TINY - I doubt you'll audibly hear it. Its transmitted at 1200Baud and there isn't that much data to transmit

Tried it last night - listening to Ch70 with squelch off & initiated a ship to ship call. You can clearly hear a burst of data similar to the sound of an old fashioned modem. It lasts maybe 1/2 sec or less, but is very obvious. It could be a useful technique in diagnosing a DSC radio.