Author Topic: FSK to USB interface  (Read 518 times)

orion_jb2001

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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?

Discriminator

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Re: FSK to USB interface
« Reply #1 on: 06 Feb 2022, 08:46:35 »
Normally, you shouldn't have to worry about the COM port settings, but the speed to the PC is 19200 8N1 as well.

You can use a serial port monitoring program to see the data sent to the PC.

orion_jb2001

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Re: FSK to USB interface
« Reply #2 on: 06 Feb 2022, 09:09:50 »
Thanks for the reply Rene.  I found an interesting site that make reference to settings for working with FTDi chips.  It makes an interesting suggestion about advanced settings of your com port when using FTDI chips. https://www.digi.com/support/knowledge-base/optimizing-usb-to-serial-port-settings.  The standard 9600 bit per second is shown however there is a vast difference in the receive bytes, transmit bytes and latency speed settingsin advanced settings.  I am trying these at the moment and a noticeable difference in regards to "cleaner" messages being displayed, that is not as many garbles which sometimes appear.