New UK 76GHz distance record

A new distance record of 102km was achieved on 76 GHz Saturday 14th September 2013, a contact between Batcombe Hill, Dorset (IO80RT59) and Eglwysilan Mountain, Gwent (IO81IO36). This is also believed to be the first 76 GHz contact between Wales and England.

Operating on three mm-bands, 24, 47 and 76 GHz, were Chris Towns G8BKE and John Hazell G8ACE at Batcombe Hill and also on the three bands at Eglwysilan was Ian Lamb GW8KQW, and with the valuable assistance from Keith Winnard GW3TKH who was also operational on 24GHz.

All three bands were worked using NBFM with full duplex operation on 76GHz between GW8KQW and G8ACE with one way FM between G8BKE and G8KQW. Signals on 76GHz were exchanged for over two hours with a very gradual increase in average signal strength after some QSB initially.

Both Tx and Rx were locked using RDDS PLLs at G8ACE and the GW8KQW Tx RDDS1 locked. This was the first time RDDS locking was used at both ends and meant the 76GHz signal was acquired within seconds due to the highly accurate frequency control therefore no tuning required. References used for the PLLs were 10MHz double oven OCXOs which are readily available on ebay.

It has been very difficult to improve on the previous record distances primarily due to the earth being curved. So far if the path is not optical then it doesn't work, none of this K=1.33 stuff on 76GHz with the relatively low power levels used.

This tremendous success is a result of continual innovation and systematic improvements and testing of the equipment built and used by the Wessex microwave enthusiasts with support from other microwave radio enthusiasts in UK and Germany.

By calculating the link budget and path loss of this path it was possible to predict what environmental conditions would potentially give sufficient margin for success. The 7 day weather forecasts (specifically the dew-point temperature) have been analyzed for several weeks whilst waiting for the optimum conditions to materialise.

We are indebted to Keith GW3TKH for the suggestion of this path which is LOS and for his assistance in guiding Ian G8KQW up the Welsh mountain, without Keith’s suggestion and support this would not have been possible.

Ham Radio: Helping to Build a Fast and Free Internet

Noisebridge from San Francisco are working on a project using commodity Wi-Fi equipment modified to work under amateur radio frequencies

The FCC grants experimenters spectrum space to build high power, long range radio systems. Through this provision, Noisebridge has begun building the HInternet (a combination of “Ham Radio" and “Internet”).

Quest article - http://science.kqed.org/quest/2010/09/21/ham-radio-helping-to-build-a-fast-and-free-internet/

Noisebridge Hackerspace Hinternet project - https://www.noisebridge.net/wiki/HInternet

Noise Floor Study

The RSGB’s legacy committee has agreed a submission for funds to advance the above study.

The new funds will allow an extension to the original Campaign, which is to be titled 'Noise Floor Study', and will include university involvement.

To further the Campaign, part of this initiative requires more input devices scattered around the U.K. The suggested Rx. is the Sentinel SDR Rx. and an active aerial, both sold by Cross Country Wireless.

Ideally there should be at least one Rx. in a quiet/Rural location, so that comparisons can be made with more noisy locations, and as a basis for final analysis.

One of the reasons why more Rx’s are not in the field right now I guess is, the price; both the Rx. and the aerial cost around £169.00 each plus P+P. The controlling software runs on Windows XP or Windows 2000, so older PCs/Laptops can be utilized. Perhaps groups such as affiliated societies could consider purchasing the units, to install and maintain them as a group project.

As part of the legacy funding, a web site will be established to at least display the Sentinel reported noise levels on 5 different QRG’s, each site will report their readings every 10 minutes. The display will be in the form of a U.K. map with the Rx. sites marked at the correct location with the readings. There may be other outputs, which are in the discussion process.

All that is needed is more data gathering Rx’s in all sorts of noise environments, to advance Radio Amateur’s in the general publics and scientific communities, ethos. Participation will also provide those participants with another fulfilment of the licence, and that is the gaining of knowledge through the study of the radio environment.

RSGB Annoucement - http://rsgb.org/main/technical/propagation/noise-floor-study/