stan wrote:I am trying to connect the diu to the astrtac3000 via PTP microwave, and from the comparator to the site located quantar via microwave. I belive i should set all the components to extrnal clock. can anyone provide some input from previous experience?
Thanks.
The rule of thumb is, that if your transporting the V.24 from one device across a microwave or other transmission device (i.e. lease line modem, channel bank), you should use the
clock signal being generated by the microwave / transportation device itself. A typical installation from days gone by, used Permisys (now named Zhone) channel
banks to transport the 9600 baud sync (V.24) circuit (via SRU card), as well as 4 wire audio (E&M card or DSM II) across the microwave, as part of a T1 carrier. The idea is to let the
timing of the T1 channel itself dictate the clock of the circuit as well. This allows the data to stay in sync across the entire microwave, thus preventing lost V.24 data bytes.
In the case of the channel banks, the Sub Rate Card (SRU) generates the clock signal to gate in or out the data from the DIU or Astro Tac 3000, or between DIU or Astro Tac 3000 and Quantar etc.
There are two settings on the wireline card (Switch 1 on, switch 2 off, or Switch 1 off, switch 2 on – this is the only choices)- one for internal sync, and the other is external sync. Internal sync is when
you have two devices in the same general area, where you can run a "Null" V.24 cable (cross over cable) between the devices, and since they are so close, there isn't anything electronic that could delay the signals. The external setup allows the user to use straight through V.24 cables, between the device and a Premisys channel bank SRU card.
In the case of your PTP microwave, check to see if their V.24 interface supports external clock. You really should use it in the transportation of sync V.24 on the microwave.
I’ve done quite a bit of these connections, bring astro tac receivers and or Quantars back to Astro Tac 3000 comparators.
B.