Microwave DATV activity

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g8gtz
Posts: 1733
Joined: Wed Apr 07, 2010 6:26 pm

Microwave DATV activity

Post by g8gtz » Sat Oct 02, 2021 12:28 pm

Dave GW4FRE and I went out last Monday in an attempt to increase the distance worked on 47 and 76 GHz and to put a couple more QSOs on the BATC 5.6GHz ladder https://batc.org.uk/contests/6cm-ladder/

Both stations ran Langstone and Portsdown combos driving transverters on each microwave band. The Langstone was always used for dish alignment and initial narrow band QSOs, except on 5.7GHz where the signals were very loud and we went straight to DATV.

Dave went to IO81LS (Blorenge mountain) near Abergavenny and I started at Birdlip IO81WU near Gloucester. The path is a line of sight over 67km with a calculated loss of 175dB on 47GHz and 182dB on 76 GHz.

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5.6GHz went very easily with an MER of over 20.

We managed a 2-way DATV QSO on 47GHz with MERs of 7 dB and 10 dB (Dave runs more power than me).

We managed a narrow band QSO on 76GHz but failed on DATV even at 125ks.

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I then moved to Cleeve Common above Cheltenham IO81XW with a 74km path and path losses of approximately 3 dB more than Birdlip.

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Again 5.6GHz went very easily with an MER of over 20 and again we managed a 2-way DATV QSO on 47GHz with MERs of 4 dB and 7dB reflecting exactly the increased path loss. 76GHz failed on DATV not surprisingly but we did manage a NB QSO which is not bad at 75kms.

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A good day out which proved we are being too optimistic with 76GHz, next time we will start at 25km and work out from there, but we did prove it is possible to have a DATV QSO on 47 GHz over 75+ km.

73

Noel - G8GTZ

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