[hpsdr] Pactor on PowerSDR

[Scott Traurig]

If PACTOR requires <35mS of T/R turnaround time then it is probably not
possible to use it at any sample rate. Audio path latency is essentially
independent of the primary sample rate, e.g. 384kHz, and is on the order of
30mS per direction using the radio internal CODEC connections, i.e. the
front and rear panel audio connections. So turn around time will be 60mS
total, plus the few milliseconds required to actually switch from T to R.

73,

Scott/w-u-2-o






On Wed, Aug 3, 2016 at 3:34 PM, John Laur <johnlaur at gmail.com> wrote:

> ***** High Performance Software Defined Radio Discussion List *****
>
> Hi, Gary.
>
> The PACTOR modems require a ridiculously fast T/R turnaround time in
> the radio. This must be <35ms with PACTOR II. While the current
> releases of PowerSDR can be configured to be *almost* this fast and
> are indeed much faster than any other direct sampling SDR today, the
> DSP latency present in the software chain plus the use of relay
> switching, etc. means that it will be basically impossible to get a
> hardware PACTOR modem working reliably without significant
> modifications to the software and possibly the hardware.
>
> PACTOR's strict TR turnaround requirements are in fact a problem for a
> large number of current non-SDR radios, particularly those which rely
> heavily on DSP functions or use very safe (slow) timings on their T/R
> relays.
>
> All that being said, you may be able to experience some limited
> success by running the sampling rate up to the maximum 384kbps,
> choosing the minimum phase filters available since PowerSDR 3.3.8, and
> reducing the buffers and relay delays as much as you are able to avoid
> hot switching. You will still likely be right at the edge of the
> threshold.
>
> There is some buffering in the onboard audio codec and network rx/tx
> buffers in order to handle a small amount of network jitter. Some
> users have been able to get slightly better latency by using low
> latency ASIO devices with a high samplerate and small buffers in lieu
> of using the onboard audio, but this is not a simple setup.
>
> 73, John K5IT
>
> On Mon, Jul 18, 2016 at 8:24 AM, Gary <gibog1 at iinet.net.au> wrote:
> > ***** High Performance Software Defined Radio Discussion List *****
> >
> >
> > I am having no luck using an SCS PTCII usb Pactor modem running
> Winlink2000 on an ANAN 100D
> >
> > Audio connections Via line in and line out on the db25 connector and
> running powersdr in digital mode.
> >
> > I can successfully connect using Winmor but not with the pactor modem.
> >
> > Has anyone had any experience with this issue?
> >
> >
> >
> > Gary VK8BN
> >
> >
> >
> >
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