Topics

1

Data Slicers and Interfaces / FSK to USB interface

« on: 05 Feb 2022, 23:12:36 »

Just a question on the USB connection interface.  In the very good description suppplied:
##The incoming signal is sampled with 5 times the data rate. So e.g. a FLEX-1600 signal is sampled 8000 times per second

The transitions from 0 to 1 and from 1 to 0 are used for bit synchronisation. Ideally, when receiving data, these 5 samples will be 11111 or 00000. If the 5 samples received are e.g. 11110 or 10000, resynchronisation needs to take place: one sample to the right resp. one sample to the left

The majority of the 5 samples determines whether a 0 or 1 bit has been received

When 8 bits have been received, these are sent to the USB module observing the standard RS232 protocol with 19200 bit/s , 8N1 (8 data bits, no parity bit, 1 stop bit)##

A great description of what happens with signal to the USB module, but what about from the USB module to your PC/laptop?  Relating to the reference in bold, the RS232 protocols, it mentions 19200 bits, is that what you should have your com port to the computer set at or what should your relevant com port be set to, for connection to you PC?

2

Data Slicers and Interfaces / FSK to USB Interface - resistor required??

« on: 21 May 2020, 12:08:51 »

Hi all,

Just doing some tiding up with the scanner, appreciate the need for the resistor of a discriminator tap to protect pc sound cards etc, but do you need to put in a resistor for a usb interface??

3

PDW Support / Hmmm FSK to USB interface

« on: 05 Feb 2020, 02:08:28 »

Ok, just installed the interface.  Decoding pocsag 512 only.  Dip switches set to off (although the pdf manual shows all dip switches on, despite what the setting words state....)  USB drivers installed, com port selected.  Meter indicating receiving signal during scanning. 

Now the interesting bits:   PDW 3.12 options set at enable pocsag decoding 512, and that is it.   Using the discriminator, it is decoding signals, however all are showing numeric.    Hmm I thinks, using these same settings before attaching the USB interface, I was receiving alpha decodes on some of these addresses that are on the USB interface now, only showing numeric.

Fault check.  reconnected the sound card option, same options, receiving well decoded alpha text messages again on the same addresses where on the USB interface, are producing numeric scans.