Link margin needed : Jovian system, Morse Code ...


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Message boards : Science (non-SETI) : Link margin needed : Jovian system, Morse Code ...

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Message 1096739 - Posted: 13 Apr 2011, 7:20:14 UTC
Last modified: 13 Apr 2011, 7:40:13 UTC

I am interested in the what the link margins are to the Jovian system when one is not using modern digital signalling or modulation systems. This is not a radioteletype link margin problem.

--http://en.wikipedia.org/wiki/Link_margin
--http://en.wikipedia.org/wiki/Link_budget
--http://en.wikipedia.org/wiki/Friis_transmission_equation

There is this urban legend that a Morse Code message was sent there, and a Morse Code message was received back. No other useful data comes with the urban legend, so for the RF engineer it is somewhere between unhelpful and useless.

As Jupiter is considered to be a pulsar (just not one of the stellar kind) -- this seemed to me to be a totally crazy link margin to attempt.

Because one is dealing with an urban legend
-- the frequency band is unspecified
-- the data rate is unspecified
-- the modulation type is unspecified
-- the antenna polarization is not stated either, but how this would be important is unclear (LHCP or RHCP forced by nature?)

I would love to see a table or spreadsheet (xls, or Open Office format), using 100 MHz steps starting at 100 MHz and terminating at 15 Ghz ... USING in table columns

-- FM (wideband, -/+ 75 Khz)
-- FM Narrowband (12.5, 25) Khz
-- AM (On/Off) Keying
-- AM Modulated Tone

Modulation issues
-- Pure tone, no harmonics
-- 2nd, 3rd harmonics assuming 6db suppression per each harmonic step
-- Filtering, as raw Morse Code creates substantial wideband "splatter" as its datarate increases

And looking at data rates of 10 WPM, 20 WPM, 30 WPM, 40 WPM, 60 WPM, 80 WPM.

The DSN link equasions, the so called "energy per command bit" are totally worthless for this kind of link equation -- as Morse Code dots and dashes have different durations and can be modulated differently. The radioteletype formats used by the DSN to send remote commands are bound by different link margin laws than Morse Code signalling.

The DSN network does not provide any online link margin calculators for the general public, as the DSN in general wants to avoid contact with the general public. Jodrell Bank, nor CSORO Parkes do this either so it is more of an industrial relations disease.

What must be taken into account
-- http://en.wikipedia.org/wiki/File:TerrestrialMicrowaveWindow.jpg
-- http://en.wikipedia.org/wiki/File:Radio_emissions_of_Solar_System_planets.png

To me, the urban legend seems improbable as any advanced civilizaiton would loathe the Jovian system for the same reasons as scientists do :

-- It's a seething cesspit of radiation
-- It has an environment not at all friendly to reception of RF emissions coming from outside the Jovian system

I don't see the Mythbusters TV programme taking this on, as it is beyond their intellectual grasp. Sadly, no lecturer at the SETI Institute has done this either to spice up their sometimes exceedingly dull lectures as seen on YouTube.

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Message 1096787 - Posted: 13 Apr 2011, 12:13:06 UTC - in response to Message 1096739.
Last modified: 13 Apr 2011, 12:15:12 UTC

I am interested in the what the link margins are to the Jovian system when one is not using modern digital signalling or modulation systems. ...

There is this urban legend that a Morse Code message was sent there, and a Morse Code message was received back.

... And looking at data rates of 10 WPM, 20 WPM, 30 WPM, 40 WPM, 60 WPM, 80 WPM.

... To me, the urban legend seems improbable as any advanced civilizaiton would loathe the Jovian system for the same reasons as scientists do :

-- It's a seething cesspit of radiation
-- It has an environment not at all friendly to reception of RF emissions coming from outside the Jovian system

I don't see the Mythbusters TV programme taking this on, as it is beyond their intellectual grasp. Sadly, no lecturer at the SETI Institute has done this either to spice up their sometimes exceedingly dull lectures as seen on YouTube.


If you were to look for long enough at all the clicks and bangs that Jupiter transmits, and you were to use enough permutations of data filtering, you are almost guaranteed to find some Morse code in amongst all the random rubbish.

It's a bit like playing a game of the "Bible Code"... Far more significant is to follow the SETI requirements and look for something that is consistent and repeatable and not natural.


Aside: For the same reason, "anti-virus" software as often used on Microsoft Windows systems will find all manner of virus signatures in the WU data from s@h (as false positives). Given enough random data, you can randomly create any virus signature you like!


So, for Jupiter, was that one lightning strike or a few million?

Keep searchin',
Martin
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Message 1097339 - Posted: 15 Apr 2011, 3:46:13 UTC - in response to Message 1096787.


If you were to look for long enough at all the clicks and bangs that Jupiter transmits, and you were to use enough permutations of data filtering, you are almost guaranteed to find some Morse code in amongst all the random rubbish.

It's a bit like playing a game of the "Bible Code"... Far more significant is to follow the SETI requirements and look for something that is consistent and repeatable and not natural.


Aside: For the same reason, "anti-virus" software as often used on Microsoft Windows systems will find all manner of virus signatures in the WU data from s@h (as false positives). Given enough random data, you can randomly create any virus signature you like!



I had an outage at my internet provider, so was not able to fully finish editing the posting. So perhaps the posting's wording is not perfect. Still, in spite of the botch there was not much room left for alternate interpretations as far as I can tell.

My concern was about weather a Morse Code message could make it to the Jovian system intact, and at what speed -- and modulation format etc...

How you got this alternate idea of what I was looking for is beyond me.

This is a good and very valid telecom question, as except for Earth-Moon-Earth circuits all solar system telecommunications uses some form of RTTY and not Morse Code.

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Message 1097392 - Posted: 15 Apr 2011, 7:25:45 UTC

It's a bit like playing a game of the "Bible Code"...


Drosnin also made a number of claims and alleged predictions that have since failed. Another claim Drosnin makes in "The Bible Code II" is that the nation of Libya would develop weapons of mass destruction that they would then be given to terrorists who would then use them to attack the West (specifically the United States) In reality Libya improved relations with the West in 2003 and gave up all their existing weapons of mass destruction programs.


Ooops

However, I am quite sure that a message of some sort whether Morse or not could be easily sent to Jupiter but I would imagine the odds of a genuine reply are somewhat sparse. Not only bible code, but others can find what they want to find in data, take Duncan Lunan, "We live on the sixth planet of seven, coming from the sun, which is the larger of the two.... etc"

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Message 1097448 - Posted: 15 Apr 2011, 12:19:04 UTC - in response to Message 1097339.
Last modified: 15 Apr 2011, 12:21:26 UTC

... My concern was about weather a Morse Code message could make it to the Jovian system intact, and at what speed -- and modulation format etc...


Easily done. Any Radio Ham that can do EME could do that.

Also, NASA do that kind of thing on a daily basis.

For all the artificial data we've beamed to the Jovian system, we've only ever received replies from our own space probes.


Aside: I believe earth-bound radio telescopes have listened in on the Jovian lightning.

Keep searchin',
Martin
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Message 1097495 - Posted: 15 Apr 2011, 14:50:44 UTC
Last modified: 15 Apr 2011, 14:52:42 UTC

As a duly licensed amateur radio operator, I can tell you that a Morse Code signal can reach its intended destination more easily than any other form of modulation. When nothing else can get through, Morse Code frequently can. As was observed, more complex signals are regularly sent to and from Jupiter, and even farther afield, due to our space probes. The technical possibility of sending or receiving the signal does not seem to be of the essence. The problem here would be to determine if there is any substance to what you call an 'urban legend'. You give no source or citation that could be checked, with this goal in mind. Without such a lead, I don't see how much can be made of this claim. Where did you hear of this 'urban legend'? Who is supposed to have sent the signal to Jupiter, and why? What was the alleged content of the message sent? What message was claimed to have been received in reply? Michael

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Message 1104061 - Posted: 7 May 2011, 10:59:54 UTC - in response to Message 1097495.
Last modified: 7 May 2011, 11:01:08 UTC

I can only remember the Morse return message, and this is what Google says about it :

http://www.google.com/search?sourceid=chrome&ie=UTF-8&q=%22we+were+not+talking+to+you%22

I am more interested in solving the link margin problem, but like I say the Deep Space Network link equations work only for non-CW emissions like

-- BPSK
-- FSK
-- etc ... as Voyager craft for example use (2002 data)...

The Deep Space Station (DSS) transmits an uplink carrier frequency of 2114.676697 MHz to Voyager 1 and 2113.312500 MHz to Voyager 2. The carrier may be unmodulated or modulated with command (CMD) or ranging (RNG) data or both.

Phase lock to the uplink carrier is provided. When the transponder receiver (RCVR) is phase locked, its voltage-controlled oscillator (VCO) provides a frequency reference to the exciter to generate a downlink carrier that is two-way coherent with the uplink.

Voyager receives and demodulates the command signal from the uplink carrier. The signal consists of 16-bps, Manchester-encoded commands, bi-phase modulated onto a squarewave subcarrier frequency of 512 Hz.

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Message 1104106 - Posted: 7 May 2011, 14:27:32 UTC

Writer Rupert Matthews 2008 book, referenced in the linked article, appears to be the only source for this claim. He says he had a NASA informant, but others, trying to confirm this story, have been unable to do so. An interesting story, but it will have to remain in what Stanton Friedman calls 'the grey basket'; neither black nor white, neither definitely known to be either true or false. Sorry, but I don't have the technical information about signals that you are seeking Michael

Message boards : Science (non-SETI) : Link margin needed : Jovian system, Morse Code ...

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