[ntp:questions] Adjust serial device speed in ACTS refclock driver?

Rich Wales richw at richw.org
Mon Oct 6 06:18:34 UTC 2014

Replying to Brian Inglis:

> Modem cards would run at whatever interface rate the system set,
> e.g. 19,200 or 115,200, and use the remote connect info to set the
> line speed.

I would normally expect a "sane" modem to act as you described.  But
this TrendNet TFM-561U appears to be tying the telco line speed to be
the same as the system serial port speed.

> The NIST ACTS supported range is 1,200-9,600. . . .

I have tried connecting manually (via the "cu" command), and if I use
any local serial port speed other than 1200 bps, I am completly unable
to connect to the NIST ACTS -- the modem noise cycles through several
different tones, apparently trying to negotiate a mutually acceptable
speed, but eventually it times out and hangs up.

I tried both init strings you quoted from the Amazon review, but no
luck unless I used a local speed of 1200 (cu -l /dev/acts0 -s 1200).

As for "the modem connects to my ISP just fine but was really slow" --
remember, I'm not trying to use this TrendNet modem to connect to an
ISP -- I'm only trying to use it to connect to the NIST ACTS.

Rich Wales
richw at richw.org

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