[RTTY] 4-port serial card for Windows 8.1 results

[Joe Subich, W4TV]

On 4/25/2014 11:38 AM, Don AA5AU wrote:
 > Tom et al, the reason I went with the standard serial port board in
 > my new PC is because most USB-to-serial adapters will not handle
 > 5-bit data. I think the Edgeport does, but most do not.

Actually, USB to serial adapters will handle 5 bit codes.  The problem
is that all USB to serial UART (or "Bridge") chips designed in the last
10 years support USB 2.0 data rates and are intended to handle up to
one Mb/s or higher (typically, 2 or 4 Mb/s).  When they become widely
available, USB 3.0 UARTs will probably increase the minimum supported
speed even further.

UARTs set their data rate using what is known as a bit rate divider -
that is a 14 bit binary number by which the chip's clock (crystal) is
divided to create the output bit rate.  2^14 = 16,384 and 1 MHz (1 Mb/s)
divided by 2^14 = 61 Hz (or 61 baud).  Thus USB to serial converters
produced in the last 10 years or so simply can not operate *slowly*
enough to handle 45.45 (or 45) baud.  The typical minimum speed is
110 or 300 baud.

The Edgeport products are unique in a couple of ways.  The manufacturer
does not use an off the shelf USB UART or Bridge - they are built on an
Intel microprocessor (note: microHAM's DigiKeyer, microKEYER, Digikeyer
II, microKEYR II, micro2R and MK2R+ use an ATMEL microcontroller for
the same function).  Secondly, since the Edgeport products are/were
intended primarily to support terminals, scanners and other devices
that generally operate at low data rates, they support data rates below
300 (or 110) baud missing from the other USB to serial devices rather
than the megabit rates used by data storage and transfer devices.

73,

    ... Joe, W4TV


On 4/25/2014 11:38 AM, Don AA5AU wrote:
> Tom et al, the reason I went with the standard serial port board in my new PC is because most USB-to-serial adapters will not handle 5-bit data. I think the Edgeport does, but most do not.
>
> For years I have been running a laptop and a Sigi 4-port USB-to-serial adapter for FSK/PTT and radio control on my second radio. In WriteLog, I used "Software generated FSK" and all worked well until the BARTG 75 contest came up. WriteLog's "Software generated FSK" does not support 75 baud RTTY.
>
> In order to run SO2R in the BARTG 75 contests, I was forced to run both radios on my one PC that had 5 legacy serial ports. I do not like SO2R on a single PC (too busy for me), so I'm looking forward to doing my standard SO2R on two PC's during BARTG 75 on Sunday!
>
> 73, Don AA5AU
>