Hi Stefan, Luis, LF,

Yes, yes! Please grab some paper and start drawing those circuit
diagrams! ;-)

The non-engineers have many questions...

If I understand this correctly... with the NEO-M8T then I just need
one module... use one time pulse pin for LO and the other one for 1
PPM to discipline the sound card? Else with the NEO-6/7 or M8N I
need two.

For the older modules U-blox says they use a 48 MHz NCO and that the
time pulse output will have less jitter if configured to a frequency
which divides evenly into 48 MHz. So I guess 120 kHz...

But I couldn't find any information about the oscillator frequency
for the M8T. Does anybody know?

What kind of mixer?

Can filters help? Band pass filter on antenna input to mixer? LPF on
LO to mixer?

Probably more questions but since I am not an engineer and have
never seen a diagram of this, I don't know what else to ask.

Can the same LO and mixer be used for a tx up-converter?

73,
Paul



On 12/19/18 3:22 AM, DK7FC wrote:
> Hi Luis, LF,
> 
> I agree, this is indeed the most reasonable design. Using the same here 
> ;-) but a 125 kHz LO, locked to GPS.
> Maybe we should provide easy converter crcuits. A compromise between 
> high end and easy to build up, for the 'EbNaut-newcomers'?
> 
> 73, Stefan
> 
> Am 19.12.2018 07:39, schrieb VIGILANT Luis Fernández:
>> Hi EbNaut
>>
>> I think that using expensive receivers is NOT the way to go. I'm using 
>> a simple mixer as downconverter. The LO is 120KHz generated from a 
>> uBlox GPS. So the 137KHz outputs as 17KHz and can be feeded to PC 
>> soundcard. The second channel of GPS provides 1pps to discipline the 
>> soundcard using Spectrum lab
>>
>> Not using filters at all and no amplifier stages. So there is room for 
>> improvement, but it works
>>
>> 73 de Luis
>> EA5DOM