Topics

GPS and BITX

qonita.salimah@...
 

Can we adding GPS module and receive GPS coordinat data with BITX? I've heard of WSPR and WSJTX method, but not really understand about that.

Thank you so much :) 

Chris Brewer
 

HI Qonita,

I haven't seen any other replies so I'll throw in my two cents. If you already have the information you need you may safely ignore this post! :)

WSPR is a low-speed protocol which really doesn't have anything to do with GPS. I assume this is also true for WSJTX.

You could theoretically connect a GPS module that uses serial communications. Arduinos have built-in UARTs just for this purpose, and it's very easy to send and receive serial data through the existing USB serial interface to/from a host computer. However, you don't want to use the USB connection- you probably want a direct serial connection.

Looking at the Arduino Nano schematic shows that the TxD and RxD lines are also brought in parallel to two IO pins, so you can theoretically connect low-level serial lines directly between the two. I haven't tried this myself, though, hence the word "theoretically".

If you wish to check for yourself, the Arduino Nano schematics are available at several places- for example, http://actrl.cz/blog/index.php/2016/arduino-nano-ch340-schematics-and-details/ .

IMPORTANT: Serial communications sometimes use RS-232 levels. These are NOT compatible with the Arduino pins!
RS-232 involves higher positive voltages and negative voltages which will likely damage an Arduino.
You are looking for a GPS module with so-called "TTL compatible" serial lines.

Hope this helps,
Chris B, AC9GN

On Tue, Mar 6, 2018 at 7:24 AM, <qonita.salimah@...> wrote:

Can we adding GPS module and receive GPS coordinat data with BITX? I've heard of WSPR and WSJTX method, but not really understand about that.

Thank you so much :) 


xminoli@...
 

Hi Qonita,
I agree with Chris, you do not have to transmit GPS coordinates.
WSPR is a protocol for testing propagation, antennas and so on.
Using this digital mode you transmit your Callsign, first 4 chars of your locator and power in dBm.
Receiving stations report transmitter they are able to heard.
GPS usage could be to transform coordinate in Locator so you can made a beacon always transitting right locator and runtime updated.
WSJTX is a program written by John Taylor (WSPR creator and Physics Nobel Prize) for operating WSPR, JT65, FT8 etc. digital modes 

Hope this helps,
Alessandro M. IU1ETR

Hans Summers
 


WSPR does not require GPS. However:

1) WSPR requires precise frequency, the transmission must be within the 200Hz WSPR sub-band.

2) WSPR requires precise timing: transmissions start on the 2nd second of even minutes, +/- a few seconds. An ordinary crystal or worse still, the ceramic resonator on some Arduinos, will not provide sufficient timing accuracy to run WSPR for long.

A GPS is a very convenient and easy way to achieve both of these objectives. On the Ultimate3S kit http://qrp-labs.com/ultimate/u3s the latitude and longitude are also converted to Maidenhead Locator which is encoded live, into each WSPR transmission. Something that is necessary if you want to use WSPR for tracking something (ship, balloon) for example the Canadian C3 expedition http://qrp-labs.com/c3

Speaking of which: Jim N2NXZ's U3S-22 balloon (running modified Ultimate3S firmware) reached Kazakhstan today. For the second time! It's already been flying for 23 days, at a little over 9,000m altitude, and completed one world circumnavigation! See http://qrp-labs.com/flights/u3s22 for details and live tracking (using WSPR) during daytime. Big congratulations to Jim!

73 Hans G0UPL