[Hackrf-dev] HackRF and Spyverter

[Martin Smith]

The spyverter (https://airspy.com/) as stated on the page can handle a maximum
power of 10 dBm (At a guess this is derived from the SMD components inside it
being rated for 125mW [~20.97dBm] and a ~10dB safety margin for any power up
initialization spikes) so as long as you stay under that, say with a physical
10dB (or 5dB) attenuator (
https://github.com/mossmann/hackrf/wiki/HackRF-One#transmit-power ), it should
be fine.

The hackRF One can easily provide the power required over Bias-T to fully power
the Spyverter (Bias-tee voltage: 4.2v to 5.5v ; Current consumption: 10mA typ).

You would inject an IF signal between 120MHz and 180MHz on the IF side and that
would be down converted to between DC to 60 MHz on the antenna side, but you
would still need to filter the output.

The default oscillator in a HackRF, from which most clocks are derived has
manufacturing tolerances and thermal operational stability. The manufacturing
tolerances is basically decided by price point, you can pay more for tighter
tolerances, or pay less and get looser tolerances.
CX3225GB25000D0HEQZ1
Specifications
Frequency: 25 MHz
Tolerance: 20 PPM
Frequency Stability: 30 PPM
Minimum Operating Temperature: - 10 C
Maximum Operating Temperature: + 70 C

So if a default HackRF One was tuned to 180MHz, each individual HackRF could be
due to manfacturing tolerances could have a frequency anywhere from 179,996,400
Hz to 180,003,600 Hz (20ppm @180MHz =+/-3600Hz), which over the entire
operational temperature range could drift by 30ppm (30ppm @180MHz = +/- 5400Hz).
The good new is that the ppm due to manufacturing tolerance is a constant
decided when the quartz crystal is cleaved (well technically it does change
slightly over years of operation, but it is easier to consider it a constant).
And once a device has warmed up (say 10 minutes) the operational ppm correction
would also be close to a constant (it may shift slightly from summer to winter
time if the ambient room temperature changes).

Before I go too far down this rabbit hole, what I'm basically saying is that
even if you bought a plugin TCXO module for a HackRF on ebay with a 0.1 PPM
(0.1ppm @120MHz = +/- 12Hz ; @ 180MHz = +/- 18 Hz) you will still need to use a
ppm (or ppb) correction to calibrate for RX/TX using a spyverter. Although maybe
a 12 Hz to 18Hz offset is ok in your particular application.


On 26/04/2018 07:03, Mitja kocjančič wrote:
> anyone knows if Spyverter can be used in oposite direction (to transmit a
> signal on 120,918Mhz and have it output on 918khz) because HackRF is realy
> weak on theese low frequencies so if it could put a solid 15dbm below 10Mhz
> it would be great
> but I am afraid to damage my Spyverter if I try this
> PS: Can I uses bias tee from HackRF to power my Spyverter?
>
> 2018-04-25 23:08 GMT+02:00 Gavin Jacobs <apriljunkbox at hotmail.com>:
>
>> Alejandro,
>> The Spyverter will shift the 457kHz signal up by 120 MHz, so the result
>> will be 120.457 MHz. Connect your 457kHz signal to the input of the
>> Spyverter; connect the output of the Spyverter to the rf input of the
>> hackrf. Remember to apply 5Vdc to the Spyverter (make sure you use a linear
>> power supply, or a battery pack, because a switch mode supply will be very
>> noisy). You can use gnuradio companion (or numerous other programs) to show
>> the spectrum.
>>
>> Jake
>>
>> ------------------------------
>> *From:* HackRF-dev <hackrf-dev-bounces at greatscottgadgets.com> on behalf
>> of ALEJANDRO RAMIRO MUNOZ <100314975 at alumnos.uc3m.es>
>> *Sent:* April 25, 2018 2:36 PM
>> *To:* hackrf-dev at greatscottgadgets.com
>> *Subject:* [Hackrf-dev] HackRF and Spyverter
>>
>> Hey all!
>>
>> I'm writing this e-mail because I'm using HackRF-One SDR as a spectrum
>> analyzer in a university project.
>>
>> I'm also using a Spyverter converter (https://airspy.com/spyverter-r2/)
>> and I'm having troubles to configure correctly the device, since I'm not
>> very familiar with it.
>>
>> I'm interested in detecting with the HackRF-One a signal which is at 457
>> KHz (out off the range of operation), therefore I need the Spyverter to
>> achieve it, but I'm not able to configure it.
>>
>> If you have some experience with this device used with a HackRF, or
>> there's any website I can get some information about how to configurate it,
>> I'll apreciate it a lot.
>>
>> Thank you very much in advance,
>> Kindest regards,
>>
>> Alejandro Ramiro.
>> --
>> Alejandro Ramiro Muñoz
>> NIA: 100314975
>>
>> Grado en Ingeniería de Sistemas de Comunicaciones
>> *(Bachelor's Degree in Communication System Engineering)*
>>
>> *Universidad Carlos III de Madrid*
>>
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>> HackRF-dev at greatscottgadgets.com
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>>
>>
>
>
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