[ARC5] A British Version of ZB?

[Bart Lee]

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On Mon, Apr 5, 2021 at 7:15 PM Bart Lee <bart.lee.k6vk at gmail.com> wrote:

Hi Wayne,
>
> The 1947 paper cited says that the UK used a "supersonic" modulation in
> order to avoid detection in the event of leakage of a modulating signal at
> MF, which for the US Navy system would be of a modulating BCB range signal at
> ~ 1MHz frequencies. Such leakage at such a lower frequency could presumably
> be detected at greater range than the 200 MHz signal.
>
> The British system was also simpler in that it did not need a second radio
> to get the intended signal. The one VHF receiver with the BFO could detect
> the intended signal.
>
> I think the UK Navy in WW II used mainly the  "Seafire" version of the
> Spitfire  with a VHF radio R-1147B:
>
> http://spitfirespares.co.uk/radio%202l.html.
>
> But I don't know if this was the homing receiver. But one comment says: "it's
> for finding your way home!"
>
> https://www.vintage-radio.net/forum/showthread.php?t=97323
>
>
> I attach a photo from that comment.
>
> The ARR-1, even though it claims to be an "Aircraft / Radio / Receiver,"
> was just a converter, to sit atop a BCB range receiver.  See below by Lud
> Sibley (x Tube Collectors) -- I attach a very old note of mine about the
> ARR1 and ARR2.  I'm still wondering about the use of subcarrier systems for
> communications in WW II, but Lud is right about the primary use as a homing
> system.
>
> 73 de Bart, K6VK ##
> -- --
> Bart Lee
>
> Texts only to: 415 902 7168
>
> www.bartlee.com
>
> {Bart(dot)Lee(dot)K6VK(at)gmail(dot)com}
> <http://www.lawforhams.com/>
>
>
>
> On Sat, Apr 3, 2021 at 4:47 PM Robert Eleazer <releazer at earthlink.net>
> wrote:
>


> The US ZB system modulated the 230MHZ signal at frequencies at around 1
>> MHZ and downconverted the signal via a VHF front end to a BCB receiver.
>> This makes perfect sense to me.
>>
>> The British carrier homing system modulated the 200MHZ signal at 23KHZ
>> ("supersonic") and then used a BFO to translate it into something useful.
>> This makes less sense to me.
>>
>> Are these two approaches the same thing?
>>
>> Wayne
>> WB5WSV
>>
>>
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