Paul, Chris and EbNaut LF,
Stefan makes a good argument for trying what you have for TX. The HP-3325A specs show a frequency accuracy of +- 5 EE-8 and stability (option 001) of +- 5 EE-6. The HP-3325A should work ok on 2200m with a message duration of 28 minutes or less.
The 180 phase reversal is easily implemented using a DPDT relay with a 1:1 transformer connected between the 3325 generator and the amp input. Drive the relay with the RS-232 RTS or CTS signal from the computer running ebnaut-tx.exe found on http://abelian.org/ebnaut/ such that the relay shifts the phasing of the input to the transformer.
Time and frequency are important on the decoding end. Try to get them as accurate as possible on the TX end.
For 2200m a good starting message format is:
Code: 8K19A Symbol Period: 3 CRC: 16 Characters: 5 Duration: 25:36.00 Repeat on the hour and half-hour
Announce your beacon and give it a try. Lot’s of LF EbNaut listeners to let you know if it’s working out...
Comments and other suggestions are welcome.
73, Rob - K3RWR
BPSK transitions cause key clicks with non linear transmitters / amplifiers. As a practical matter ... with the high Q transmitting antennas in use ... and that it's unlikely you'll have next door neighbor interested in LF reception ... it hasn't been a much of a problem.Jay W1VD----- Original Message ----- From: "DK7FC" <[email protected]>To: <[email protected]>Sent: Monday, December 10, 2018 11:08 AMSubject: Re: LF: LF and VLF EbNautHi Paul,
Am 09.12.2018 20:02, schrieb N1BUG:
The first thing people want
to know is what equipment is required for LF EbNaut and how much is
this going to cost? But answers are hard to come by. I could never
get an answer as to whether my HP 3325B with high stability option
was good enough.
The problem is also on the other side. I don't know what a HP3325B is, or, at least, i don't know the technical details since i don't own one. So i can give no advice how to use it for EbNaut transmitting
Also there are different methods and each radio amateur is convinced about his own design.
Some methods may be easier to realise but less precise and less flexible. So based on the skills and needs and parts available one will decide for a certain design.
Thus it is not so easy to write up 'the' way to go, there are many ways. For example, there could be a 'how to EbNaut' including Linux components like ebkey, which will be useless for someone who insists to avoid using Linux...
So if you're asking the group, then you will get different advice, from different designs. And this will be confusing! So concentrate on the basics and then choose your own design.
I suggest to start in steps, don't plan to build the perfect system until the season is over.
Basically all you need is an absolutely stable signal generator and a tool for inverting the phase and managing the timing. This can be done with Windows and Linux.
I think you are one of those who avoid using Linux. So then, you need SpecLab to generate the PSK.
But step 1 is the stable signal.
One method is to use an up-converter and SpecLab to generate EbNaut. SpecLab can generate a tone on e.g. 12500 Hz which is then mixed with 125 kHz, so there is an output at 137.5 kHz. This is how i do it here.
I can tell you about other methods but this may lead to confusion already.
Maybe there is one step before step 1, call it step 0: You need to decide, "YES i will now start to transmit EbNaut and i will buy to necessary components, learn what is necessary to understand, knowing it means effort!"
What kind of signal generator do you use now?
When I asked about amplifiers for EbNaut I was told
linear is a must
Do you remember who said that?
but now I find people are doing it with nonlinear
amplifiers
Yes, a linear amplifier is not needed. It is BPSK, the output power is always at 100%, which is good :-)
73, Stefan
|
