[cma-l] Singing posters and talking shirts stealing from your FM signal...

Fri Mar 10 14:22:25 GMT 2017

Sounds like it is is a new version of "the rusty bolt"!

I just discovered today that my company has just employed a PhD student to
look at this technology.  They are "uber-clever" chaps in our R&D
department, so I think there might be something in it....

Glyn

On 10 March 2017 at 13:26, <tlr at gairloch.co.uk> wrote:

> Sort of, in that it is a product of intermodulation, but it's not
> 'spurious' in the sense that it is deliberate and controlled, chosen
> hopefully not to cause interference.
>
> A plant is only a weed if it's not wanted!
>
> Alex
>
> On 10 March 2017 at 12:03 Ian Hickling <transplanfm at hotmail.com> wrote:
>
>
> So - for "backscatter" read "spurious sideband"?
>
>
> Ian Hickling
>
> Partner
>
> <http://www.transplanuk.com/>
>
> *Office: 016 3557 8435  (07h to 22h GTS)*
>
> *Car: 075 3098 0115 (only responds when driving)*
>
> *6 Horn Street, Compton, NEWBURY, RG20 6QS*
> ------------------------------
> *From:* cma-l-bounces at mailman.commedia.org.uk <cma-l-bounces at mailman.
> commedia.org.uk> on behalf of Alex Gray, Two Lochs Radio <
> tlr at gairloch.co.uk>
> *Sent:* 09 March 2017 13:30:55
> *To:* 'The Community Media Association Discussion List'
> *Subject:* Re: [cma-l] Singing posters and talking shirts stealing from
> your FM signal...
>
>
> They don’t seem to be talking about inserting additional RDS data Ian, or
> indeed interfering with the RDS subcarrier in any way. If they only wanted
> data they point out they could use Bluetooth BLE, but this can’t carry
> audio. Their focus is on creating audio streams, and the option for data is
> simply to use the audio channels they are creating to carry FSK encoded
> data (ie a modem method). They needed massive error correction to achieve
> good data at a range of more than 2 metres, so the real throughput is
> reduced greatly.
>
>
>
> One of the three schemes they describe is ‘overlay backscatter’ in which
> they “overlay arbitrary audio on ambient FM signals to create a composite
> audio signal that can be heard using any FM receiver”. They propose
> generating this in the first or second adjacent channel (eg a few hundred
> kHz away from the host signal) because broadcast planning means that is
> almost always guaranteed to be empty
>
>
>
> Band II FM transmitters of 50nW or less don’t require a licence in the UK,
> so maybe they could get by with this for the audio version. However, they
> say they can achieve a range of up to 60 feet, which would usually need
> more like a microwatt of effective power.
>
>
>
> For using potentially white space in the multiplex spectrum they have
> Stereo backscatter which applies to stations that are essentially mono
> audio but do broadcast a stereo multiplex (eg news/talk stations). They
> backscatter data and audio on these to achieve what they say is “a low
> interference communication link.” Note not ‘interference free’!
>
>
>
> They also have a subsidiary technique to trick FM receivers receiving mono
> FM signals by inserting the stereo pilot signal and inserting their own
> audio interference free as the stereo subcarrier – effectively locally
> turning the mono station into a stereo one (that doesn’t seem a very novel
> or complex idea, and easily workable, but how many powerful FM stations
> operate in mono mode nowadays?).
>
>
>
> Their third scheme requires two or more smartphones to cooperate to set up
> a sort of MIMO wireless scheme to null out the main FM transmission and
> give them cleaner reception of the intermodulated parasitic signal.
>
>
>
> NB any unlicensed use of RDS for non programme-related data (“private
> data”) is prohibited at the moment. The coming of RDS2 might make it a lot
> harder for them to make used of ‘unused portions of the stereo signal”
> since RDS2 fills in a lot more of the ‘white space’ in the current
> multiplex spectrum.
>
>
>
> But there’s still the question of legal provisions on unauthorized use of
> somebody else’s electricity (which have somewhat dubiously been used to
> prosecute hackers!), and of unauthorized interference with radio broadcasts.
>
>
>
> Alex
>
>
>
> *From:* cma-l-bounces at mailman.commedia.org.uk [mailto:
> cma-l-bounces at mailman.commedia.org.uk] *On Behalf Of *Ian Hickling
> *Sent:* 09 March 2017 12:31
> *To:* The Community Media Association Discussion List <
> cma-l at mailman.commedia.org.uk>
> *Subject:* Re: [cma-l] Singing posters and talking shirts stealing from
> your FM signal...
>
>
>
>
>
> I think it's intimating that it can add on data in unused parts of the RDS
> section of a multiplex signal - eminently feasible - but I'd like to see
> how that propose achieving that.
> And it would also requires licensing as a standalone transmitter.
>
>
>
> Ian Hickling
>
> Partner
>
> [image:
> https://ci4.googleusercontent.com/proxy/2SkDsnIzSZgRbNnNKBSiwxiFhFQWRGV55mTjVL23fulnJpstZmYxeKrrYefY4qxiSgkMrAETld64XINLXCsujE_zI5gAsQyWeCWvHixcrNYtar3Sij4YlVBgN2NSQ-n2DsgZvrnpWZlfwCQ=s0-d-e1-ft#http://www.transplanuk.com/wp-content/uploads/2014/07/transplan_UK_weblogo_190x60.png]
> <http://www.transplanuk.com/>
>
> *Office: 016 3557 8435  (07h to 22h GTS)*
>
> *Car: 075 3098 0115 (only responds when driving)*
>
> *6 Horn Street, Compton, NEWBURY, RG20 6QS*
> ------------------------------
>
> *From:* cma-l-bounces at mailman.commedia.org.uk <cma-l-bounces at mailman.
> commedia.org.uk> on behalf of Associated Broadcast Consultants <
> info at a-bc.co.uk>
> *Sent:* 09 March 2017 11:56:23
> *To:* The Community Media Association Discussion List
> *Subject:* Re: [cma-l] Singing posters and talking shirts stealing from
> your FM signal...
>
>
>
> Alternatively you could say the original transmission IS indeed
> unchanged.  It is the identical signal broadcast from a big mast miles away
> and there is no way this system can change that.
>
> What it's changing is the reflection environment from what I understand.
> Maybe a bit analagous to sonar or radar.
>
> But maybe I understand wrongly!
>
> Glyn
>
>
>
>
> On 9 March 2017 at 11:42, Alex Gray, Two Lochs Radio <tlr at gairloch.co.uk>
> wrote:
>
> Exactly Ian -    I guess he means “…without *significantly* affecting the
> original transmissions…” or perhaps he’s found some new laws of physics.
>
>
>
> Interesting technique though if you read the full details. Reminds me of
> the cunning Russian passively bugged ‘friendship’ emblem that sat in the US
> Embassy in Moscow for some time. Also the (apocryphal I think) tale of the
> farmer prosecuted for lighting his house using power tapped off the near
> field of the Droitwich log wave transmitter.
>
>
>
> Alex
>
>
>
> *From:* cma-l-bounces at mailman.commedia.org.uk [mailto:
> cma-l-bounces at mailman.commedia.org.uk] *On Behalf Of *Ian Hickling
> *Sent:* 08 March 2017 22:37
> *To:* The Community Media Association Discussion List <
> cma-l at mailman.commedia.org.uk>
> *Subject:* Re: [cma-l] Singing posters and talking shirts stealing from
> your FM signal...
>
>
>
> ".......we developed a new way of communication where we send information
> by reflecting ambient FM radio signals that are already in the air, which
> consumes close to zero power.” The UW team has — for the first time —
> demonstrated how to apply a technique called “backscattering” to outdoor FM
> radio signals. The new system transmits messages by reflecting and encoding
> audio and data in these signals that are ubiquitous in urban environments,
> without affecting the original radio transmissions......"
> Oh yeah?
>
> Ian Hickling
>
> Partner
>
>
> ------------------------------
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> --
>
> Glyn Roylance - Principal Consultant
>
> Associated Broadcast Consultants <http://www.a-bc.co.uk/>
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-- 
Glyn Roylance - Principal Consultant
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