New User---Where can I find the definitions of "TX Latency" and "PTT Hang"?

[Steve Burns]

Folks:

I set up my new Hermes Lite 2 yesterday and was able to make contacts across the country on SSB with the internal PA. Before hooking it up to an amplifier, I want to make sure that I understand what values I should set for "TX Latency" and "PTT Hang". Is there a timing diagram somewhere that will show what these values mean? I want to make sure that my amp turns on before any signal is sent by the HL2. Since the amp takes 10msec or so to turn on after its PTT is pulled down, what value should I set compensate for this? I'm guessing "PTT Hang" but I want to be sure.

Thanks,

-Steve

KK7KNB

[Steve Burns]

Let me give my current guess at the timing relationships.
Assume I'm whistling into the mic and pull down the PTT pin. Then EXTTRG is lowered immediately. Then TX_latency  later a RF signal is produced.  When I turn off PTT (no longer ground it), then the RF immediately stops, and PTT_hang later the EXTTRG is no longer pulled down. Is that correct?

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[DL1YCF]

tx latency means that the TX fifo is filled with a certain

amount of data before transmitting starts. This is to avoid

underruns.

ptt_hang (as far as I know) is relevant for CW, it determines

When the radio goes back RX after the last touch of the key.

[Steve Haynal]

IIRC,Your understanding is correct

[Reid Campbell]

Are we sure about the shut down phase? When PTT is released, RF will continue until buffer is empty (latency period), then EXTTR will go inactive after PTT Hang delay. That's how I have always though it was but have never measured it.

Cheers

Reid
Gi8TME/Mi0BOT

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[Reid Campbell]

Steve, I think you replied directly to me, rather than the group, so I'm pushing this back to the group.

My understand is that the PTT hang starts after the FIFO is drained but I would need that confirmed.

Cheers

Reid
Gi8TME/Mi0BOT

On 29/06/2024 17:47, Steve Burns wrote:

Thanks everyone for your responses. I have enough info to set up the amp now safely. I'll probably measure these timings myself to be sure. I'm slightly worried that the RF stops TX_delay after PTT disabled, but that the PTT_hang interval is started by PTT disabled instead of when the FIFO is drained. Then I'll have to make sure that PTT_hang is enough longer that TX_delay to make sure I don't turn the amp off when there is still an exciter signal. (Nobody said this but no one is sure either.)

Again thanks for the information.

-Steve, KK7KNB

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