Doppler shift compensation on microwaves EME

Gajów, June 9- 12, 2016

Mirek Kasal, OK2AQ

ok2aq@amsat.org

mirek@kasals.com

http://www.urel.feec.vutbr.cz/esl/files/EME/EME.htm

Kompensacja przesunięcia Dopplera na mikrofalach EME

2. Difference between VHF and microwaves

Outline

1. Doppler shift

3. Doppler shift and weak signals

4. Ways of Doppler shift compensation

5. Transverter with LO/DDS and program Dopp

6. Conclusion

Gajów, June 9- 12, 2016

Precise Frequency Microwave EME system needs to be synchronized by atomic oscillator GPS (Cesium) or Rubidium Total inaccuracy can be maximal tens Hz - MW transverter - necessarily - IF transceiver (regular inaccuracy is in order 100 Hz) It is much better if IF TRX is also synchronized - Only when frequencies are precise and stabile the automatic Doppler shift compensation provides advantages in CW, SSB and fundamentally in digi modes. For WSJT modes the time of the PC needs also to be precise Less than 0.1 sec (synchronized by GPS or Internet)

Gajów, June 9- 12, 2016

c

vf 1

1

c

vf 2

2

12 A Echo

22 B Echo

21 Mutual

2

A Echo - Mutual B Echo

Doppler Shift

RXTX FF and Dopp Full

2 and

2 Moon on the FreqConst

RXTX FF

Gajów, June 9- 12, 2016

Why the precise frequency and Doppler shift compensation is important on MW ?

On 2 m - +/- 350 Hz On 70 cm - +/- 1 kHz On 23 cm - +/- 3 kHz On 3 cm - +/- 25 kHz On 1,5 cm - +/- 50 kHz

Gajów, June 9- 12, 2016

SKEDRXBTXB

SKEDRXASKEDTXA

FFF

FFFF

and Dopp Full

22

11

and

and CFOM

SKEDRXBSKEDTXB

SKEDRXASKEDTXA

FFFF

FFFF

2/SelfDopDxDop

2/SelfDop

(Mutual) DxDop

2

1

Gajów, June 9- 12, 2016

Gajów, June 9- 12, 2016

Program WSJT-X

WSJT-X allows Doppler shift compensation by CAT, but……..

- That is working fine if radio is possible QSY by CAT while transmitting Most of ICOMs, FT847,…….. But several has minimum step 10 Hz

Gajów, June 9- 12, 2016

- Many radios do not allow to change frequency by CAT while transmitting. Then a quasi compensation works in Tx period.

Gajów, June 9- 12, 2016

Gajów, June 9- 12, 2016

Gajów, June 9- 12, 2016

Gajów, June 9- 12, 2016

Doppler shift compensation without compromise

Gajów, June 9- 12, 2016

DTR

Gajów, June 9- 12, 2016

Gajów, June 9- 12, 2016

Program Dopp written in MATLAB

No Dopp compensation

CFOM – very perspective mode. Recommended CQ frequency is .200 kHz. All sigs are on the same frequency - simple monitoring. You don’t need to know Dx locator before.

Dx announced CQ on .150 and listening on his echo (TRX is set on .150)

We found randomly Dx without Doppler compensation and call him

Gajów, June 9- 12, 2016

Dopp used on 10GHz in conjunction with WSJT-X Echo mode by G3WDG

Gajów, June 9- 12, 2016

Gajów, June 9- 12, 2016

[1] G3WDG: Using WSJT-X for JT4 EME Operation

[2] http://physics.princeton.edu/pulsar/K1JT/small_station_eme.pdf

[3] http://physics.princeton.edu/pulsar/k1jt/wsjtx-doc/wsjtx-main-1.6.0.html (WSJT-X User Guide)

[4] OK2AQ, G3WDG: A New Method for Microwave EME Doppler Shift Compensation. DUBUS, Vol. 45, No. 1, 2016, http://www.urel.feec.vutbr.cz/esl/files/EME/Doc/Documents.html

[5] http://www.urel.feec.vutbr.cz/esl/files/EME/Doc/Dopp.m

[6] http://www.urel.feec.vutbr.cz/esl/files/EME/Doc/Dopp32.zip [7] VK7MO, OK1KIR, G3WDG: 24 GHz Grid Locator Tour using JT4f. DUBUS, Vol. 44, No. 1, 2015, pp. 99-103

[8] http://www.urel.feec.vutbr.cz/esl/files/EME/EME.htm (OK2AQ pages)

Reference

Gajów, June 9- 12, 2016

Gajów, June 9- 12, 2016

Thank you for attention