Philips Decca Navigator

[maxtech]

Can anyone out there help? I have recently become the proud owner of a 1967 F172H. It has been fitted out with a Philips Decca Navigator for which I have neither instructions nor any experience of. If anybody knows where I can obtain a copy of the operating instructions, I would be very grateful.

[Circuit Basher]

Not sure whether the Decca Navigator stations are still available or not (just checked on the Web and the UK chain was switched off on 31 Mar 00). The critical thing is whether you can buy current aero charts with the Decca lanes superimposed (which I seriously doubt).

There are a number of hits on Google for Decca Navigator:

Decca Overview (http://webhome.idirect.com/~jproc/hyperbolic/decca.html)
More Decca Info (http://www.qsl.net/g4ftc/decca/home.htm)
Irish Lights Decca Announcement (http://www.cil.ie/sh621x4178.html)

I've flown on RAF Pumas (as pax - could never get the hang of these new fangled rotary jobbies!!) using Decca to naviagte around UK, also have been in the wheelhouse of ships on trials where everyone was anxiously watching the Decca navigator lane readout!

Sorry, bin it and buy a GPS!

[Aussie Andy]

Decca was a parabolic nav system (I think) the UK (or maybe European?) equivalent of LORAN C which relied on time/phase relationships between terrestrial LF broadcast stations. I think it was instaleld for maritime use as well. I don't think it's still in use...

See http://www.google.co.uk/search?sourceid=navclient&ie=UTF-8&rls=GGLD,GGLD:2004-41,GGLD:en&q=Decca+navigation, http://www.radarpages.co.uk/mob/navaids/decca/decca1.htm, http://webhome.idirect.com/~jproc/hyperbolic/decca_hist.html, http://www.vectorsite.net/ttwiza.html#m3 etc

Andy

Circuit Basher - snap! :ok:

Most succinct definition is here: http://home.comcast.net/~neburoker1/decca-navigation-system.htmThe Decca Navigation System is an early precursor to positioning systems like the American GPS system and the planned European Galileo positioning system. It uses radio signals from three transmitters to fix a position. The receiver fixed a position by measuring the Phase shift of signals received from the three transmitters. One consequence was that positions were not unique. The system is deployed extensively in the North Sea and was used by helicopters operating to oil platforms. As was the case with Loran C, its primary use was for ship navigation in coastal waters.
Andy

[Sliding member]

I remeber when them Decca navigators became "popular" in the late eighties/ early ninties, if I rember right the Philips Decca Nav was about £800! How prices have changed.

[Mike Cross]

HM Ships had a wonderful Admiralty Pattern thingumabob with a glass front and whirly bits inside it called decometers. These were coloured to correspond with the lane colours on the overprint and twitched a bit. You took the readings off the decometers and plotted them on the chart.

If you think of the base stations as transmitting at very low frequency the signal would follow the curvature of the earth and produced interference patterns between the signals which could be detected by the receiver.

I paid hundreds of pounds for one in Guernsey years ago for a boat I owned. It gave a readout in lat and long and might even have had as many as nine waypoints that could be stored!

With the transmitters switched off you could use it as a paperweight or doorstop.

Mike

[charliegolf]

As a Puma crewman in the 80's, we used to train on Decca as an approach aid, long before mil helos had ILS.

We would fly approaches down a decca lane with the crewman giving the pilot ht and c/l info and corrections.

It was prone to atmospheric interferenc, but could be as accurate as a PAR.

It was a high workload 10 mins if you did them, and i only flew 1 real decca through cloud in 2 tours.

Those were the days!

CG

[IO540]

Is this the same Decca that was used by sailors until the early 1980s? That was accurate to within a few miles. When GPS came out, it died very quickly.

[Skylark4]

If required, Decca could be accurate to a few inches. Portable versions were made for survey work. The transmitters were portable that is. One of its finest hours was the recovery of the "lost" atom bombs after the American accident in Spain(?)
Nice doorstop Max.

Mike W

[UL730]

Many moons ago I owned a Cessna 172 and I fitted a Philips Decca Navigator. I certainly remember "chain shift" along with "slaves and masters". In retrospect - very antiquated but in its day was regarded as a reasonably reliable adjunct to VFR navigation. Brought new meaning to the acronym DME. Had a very interesting whip antenna – I frequently had sarcastic comments from fellow pilots to the effect - “What’s yer nine good buddie?”

You'd certainly have to put some pennies in the meter to get a signal nowadays.

Nice period piece. Just see one bowling up to The Antiques Roadshow with a well-kept version. Horatio Ponsenby Smythe, the aviation collectables expert would state something like "stamps were issued to commemorated the 50th anniversary of the first use of the Decca Navigator QM system on June 6, 1944" " Do you realise that this would fetch over 50 quid at auction?"

One would step back in amazement, uttering - “of course it’s not for sale……..” :ok: