Hook an antenna to your Propeller, and listen to the radio! (New shortwave prog

1235789

Comments

  • HollyMinkowskiHollyMinkowski Posts: 1,398
    edited 2009-09-02 - 21:38:30
    @Phil Pilgrim

    You would think they would run at least 1,000,000 watts at 60khz to get better range.
    That would be more than +12db from what they run now and would make a big difference.
    They waste money on everything else so why not make the time signals more usable.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    - Some mornings I wake up cranky.....but usually I just let him sleep -
    [The Bug Stops Here]
  • heaterheater Posts: 3,370
    edited 2009-09-02 - 21:50:03
    You can by alarm clocks, for about $10, around here that sync to DCF77.
    I bought one last year, it only worked for two days so I exchanged it. The next one worked for a week. At that point a got tired of running back to the shop so I cracked it open.

    The antenna is only an old trany radio style coil on ferrite rod about 4cm long. To tune it up there is cheapo capacitor soldered across it.

    Amazing it received anything.

    So there's the antenna for my Prop DCF77 receiver.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    For me, the past is not over yet.
  • HollyMinkowskiHollyMinkowski Posts: 1,398
    edited 2009-09-02 - 23:20:24
    @Phil Pilgrim

    Maybe you could wind a few hundred feet of wire onto a 10' piece of PVC pipe
    and then mount it outside for an antenna.

    Reception would be great and your wife would love it.


    LoL

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    - Some mornings I wake up cranky.....but usually I just let him sleep -
    [The Bug Stops Here]
  • Toby SeckshundToby Seckshund Posts: 2,025
    edited 2009-09-03 - 07:52:00
    The most power I put into an aerial was 500KW (real Watts). This used two 250KW sets paralleled up and stuck up an experimental multi-band array (500 ft masts). The array took it ok, but the old farm house right in front of it suffered "internal lightning". Good old days.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Style and grace : Nil point
  • HollyMinkowskiHollyMinkowski Posts: 1,398
    edited 2009-09-03 - 08:07:01
    The WWVB antenna.
    I see wires from tower top to tower top.
    WWVB_Antenna.jpg

    That antenna looks awfully close to the ground for 60khz.
    Maybe about like supporting a 10 meter dipole from
    pencils stuck in the ground. Then again, if there were
    any frackin sunspots you could probably work China
    on a 10 meter dipole that close to the ground smile.gif

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    - Some mornings I wake up cranky.....but usually I just let him sleep -

    Post Edited (HollyMinkowski) : 9/3/2009 8:14:24 AM GMT
    [The Bug Stops Here]
  • heaterheater Posts: 3,370
    edited 2009-09-03 - 09:18:26
    According their web site DCF77 has main and standby antennas of 150m and 200m height respectively.
    The tallest antenna mast in the world is KVLY-TV at 629m so they are not doing so badly.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    For me, the past is not over yet.
  • Toby SeckshundToby Seckshund Posts: 2,025
    edited 2009-09-03 - 11:06:35
    Back in the 70's there were articals in WW about 10KHz aerials, slung across Swiss mountain tops. Submarine comms probably. There is an escarpment to high masts setup in Shropshire, UK (not on the map).

    Holly·· The fact that the land under your topband aerial is sandy will help it. The effective ground will be lower than the real gound level, which is the same as the aerial being·higher up (assuming that the sand isn't full of salt water)

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Style and grace : Nil point
  • RetrobitsRetrobits Posts: 46
    edited 2009-09-03 - 16:46:50
    Slightly off-topic note - I used to have an Icom R-70A HF receiver.· It literally tunes all the way down to zero Hz, but I was convinced anything below 150 KHz was probably unusable due to analog circuit constraints.· That is, until I successfully received WWVB at 60 KHz.· This was in Los Angeles, and with an indoor wire antenna and poor ground. smile.gif

    WWVB·uses a weird modulation - it's not meant to hear by ear.· To do so, you need to tune slightly off frequency and use either the CW or USB mode.· But it was there all right.· I listened to the signal a long time (I was quite happy at that "catch"), and it followed the pattern documented by NIST.

    There is no voice signal of course - it carries a binary signal pattern.· WWV/WWVH, while carrying voice signals, also have a binary·signal as well.· On those stations, listen sometime for the low-frequency pulses - you can make them out by ear, and decode them using the pattern guide from NIST.

    - Earl
  • HollyMinkowskiHollyMinkowski Posts: 1,398
    edited 2009-09-03 - 17:44:17
    @Toby

    I always wondered if that was so about the sandy soil.

    Since dirt is somewhat conductive I wonder how far
    you could communicate by sending current pulses
    through the ground?

    If you drove 2 copper ground rods into the soil
    and separated them by say 1000' and sent strong
    DC pulses through that circuit just how far away
    could you be with a detector of some sort and still detect
    that current flow?

    If you sent really massive pulses it might be a long
    way. Like if you charged up high v capacitors and
    discharged them through the earth between the rods.

    Wouldn't it be somewhat like rf as far as propagation goes? I mean
    the signal would drop off dramatically but no matter how
    weak they became wouldn't they still exist many miles away?
    Wouldn't every possible path between the 2 rods be
    a resistor that would always carry at least some tiny fraction
    of the electron flow? Even if that path traveled from one pole
    to a point a hundred miles away and then back, there would
    have to be some small number of electrons following that
    path...it seems so?

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    - Some mornings I wake up cranky.....but usually I just let him sleep -
    [The Bug Stops Here]
  • Mike GreenMike Green Posts: 22,923
    edited 2009-09-03 - 17:54:06
    It would be like any other sheet resistance. Take a square of carbon impregnated cloth and plunk down two electrodes at opposite ends of the square, in a little bit from the edges, and run pulses of electricity between the electrodes and measure the voltages between points on the cloth. You can simulate this pretty easily on a computer with a nice graph of the voltage detected. If you used an AC waveform to excite it, you'd even get radiated RF. Most of the energy would go into heating up the sheet resistance (or ground), but some of it would radiate.
  • HollyMinkowskiHollyMinkowski Posts: 1,398
    edited 2009-09-03 - 18:37:51
    @Mike

    I just love thinking about how far signals can propagate.

    Like how you can calculate the size dish you would need
    to detect a .01 watt microwave signal sent from Alpha Centari using a simple
    1/4 wave whip antenna. The dish would be huge but if you
    built it you would be able to copy the signal after it had
    made the 4 year trip to earth smile.gif

    Doubling the size of a dish gives you a 3db boost in signal.
    A dish the size of a Direct TV dish has about 26db of gain.
    The huge Robert C. Byrd dish at Green Bank has a bit over 80db
    and one that could pick up that weak signal from 4 light years out
    would probably need something approaching 100db (I have not
    done the calcs) and the dish would really be something to look at,
    it would be so big you would have to construct it in a gravity free
    location because gravity stresses would tear it apart...I guess the
    only place would be the spot between earth and moon where the
    gravity balances to zero value. Some day such projects will
    be carried out by robots, humans could never see such jobs through.


    The light frequency radiation from a single LED travels easily
    all the way to a distant place like mars. It seems unbelievable
    but if you just think about it a little. Like if the earth was in darkness
    you could not see it with an instrument from mars but if you then
    covered the whole earth with glowing LEDs it is obvious you
    could see that from mars, so that means that the light from every
    LED makes it there, albeit only a few photons from each one.

    Thought experiments, I just love em smile.gif

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    - Some mornings I wake up cranky.....but usually I just let him sleep -
    [The Bug Stops Here]
  • HollyMinkowskiHollyMinkowski Posts: 1,398
    edited 2009-09-03 - 18:44:56
    The Byrd dish at Green Bank, note that
    it is an offset feed dish same as the little dishes
    you see on homes everywhere, except grown very large.

    GBT.JPG

    EDIT: The reason the feed is at the top of the dish and not
    at the easier to engineer bottom location like a home satellite
    dish is because that allows the dish to point at the horizon. If the feed
    was at the bottom then to see the horizon the dish would have to be elevated
    on a pedestal so you could tilt it down far enough...and it would look
    pretty silly smile.gif

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    - Some mornings I wake up cranky.....but usually I just let him sleep -

    Post Edited (HollyMinkowski) : 9/3/2009 7:04:45 PM GMT
    [The Bug Stops Here]
  • Toby SeckshundToby Seckshund Posts: 2,025
    edited 2009-09-03 - 18:46:19
    A friend and me used to talk though the ground back, when we were at school. We were about half a mile away from each other and put about 30Volts p/p into each end. My parents garden was end on to his direction but his was completely side on and so he could get about 150 ft separation to my 30 ft. It was never solid and full of all sorts of interference. One pole and the mains earth was much better.

    Kept us off the streets, I suppose.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Style and grace : Nil point
  • HollyMinkowskiHollyMinkowski Posts: 1,398
    edited 2009-09-03 - 18:58:07
    @Toby

    That is just amazing!!

    The fact that you were able to do that has to mean that
    data could be passed between distant points without
    wires and without rf or light.

    Now how could we do this with 2 props???
    The cheapest possible way of course, I'm very frugal smile.gif

    I'm guessing that the data rate would have to be low and
    that a lot of error correction might be needed and involve
    quite a bit of re-transmission, maybe 56kbps at a few miles
    would be a possibility?

    It would be fun to make 2 simple prop devices that
    could deliver phone modem speed internet to someone
    a few miles away! I know it's a simple thing to send
    wifi from a cheap router that far but this would involve no
    telltale antennas smile.gif

    What a fun idea.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    - Some mornings I wake up cranky.....but usually I just let him sleep -
    [The Bug Stops Here]
  • Toby SeckshundToby Seckshund Posts: 2,025
    edited 2009-09-03 - 19:10:03
    Holly

    I don't think your "low" speed of 56K would be posible. We were only messing about with audio so I bet 300/1200 Baud would be nearer the mark.

    There is a 1200 Baud objet already.

    As for your upside down dish. I turned my fathers dish that way so that it didnt get such a bashing from the gales. Where he lives on the south coast, there is a strait line to South America for the wind to work up some enthusiasm.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Style and grace : Nil point

    Post Edited (Toby Seckshund) : 9/3/2009 7:16:48 PM GMT
  • edited 2009-09-03 - 19:13:42
    What is the possibility of increasing the range using fractal antennas which is what a lot of cell phones use?

    I was watching a program on PBS and some·man got the idea to make fractal antennas out of learning about Mandelbrots because he was getting in trouble with his landlord who didn't allow antennas on·his balcony and·fractal antennas·helped make some cell phones possible.

    "Although the first validation of the technology was published as early as 1995 (see ref.1) recent independent studies continue to show the superiority of the fractal element technology in real-life applications, such as RFID.[noparse][[/noparse]4]"

    http://en.wikipedia.org/wiki/Fractal_antenna
  • Toby SeckshundToby Seckshund Posts: 2,025
    edited 2009-09-03 - 19:27:42
    Chuckz

    Fractal type aerials were around before 95 but they probably didn't get around to grabbing the name rights. Early (UK) Sat ae's were flat and small but that company got swamped by the evil one and the bright white dishes sprouted.

    To try and get around the ravages of the wind my father and me made a "Blind aerial" from concenteric foil rings on a window roller blind (scaled fron the SETI site). LMB in the right place and pull down the blind an there was the signal. Working out the elipses for 30 degree ele and 18 deg E/W offset was a bit mind blowing. In the end it was done with a wall, tracing paper and an overhead projector.

    We made 'us own entertainment.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Style and grace : Nil point
  • HollyMinkowskiHollyMinkowski Posts: 1,398
    edited 2009-09-03 - 19:44:39
    @Toby

    I turned the small dish I rigged up for wifi upside down
    like that as I could not aim at the horizon with it on the bottom.
    The pole did not allow it to be positioned low enough...

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    - Some mornings I wake up cranky.....but usually I just let him sleep -
    [The Bug Stops Here]
  • LeonLeon Posts: 7,620
    edited 2009-09-03 - 19:49:22
    Toby Seckshund said...
    Back in the 70's there were articals in WW about 10KHz aerials, slung across Swiss mountain tops. Submarine comms probably.

    Does Switzerland have a navy, let alone submarines? lol.gif

    Leon

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Amateur radio callsign: G1HSM
    Suzuki SV1000S motorcycle
    Leon Heller
    G1HSM
  • HollyMinkowskiHollyMinkowski Posts: 1,398
    edited 2009-09-03 - 20:47:36
    The Swiss might have been contracted to provide secret
    communications to submarine fleets.

    The Swiss are so trustworthy with secrets...NOT!
    (google UBS accounts tax)

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    - Some mornings I wake up cranky.....but usually I just let him sleep -
    [The Bug Stops Here]
  • VIRANDVIRAND Posts: 655
    edited 2009-09-04 - 05:21:10
    [noparse][[/noparse]quote] I don't think your "low" speed of 56K would be posible. We were only messing about with audio so I bet 300/1200 Baud would be nearer the mark.

    There is a 1200 Baud objet already.
    EDIT: (quote, malfunctioned ^^^)

    The frequencies that 56K telephone modems used are actually in the range of 300-3000 Hz.
    It took me awhile to find someone who could tell me how that worked at the time because
    you can't modulate 56000 pulses on a channel that only allows 3000 pulses, but it uses
    phase modulation, either Quadrature AM (sine+cosine dual carrier on same frequency)
    or Quadrature Phase Shift Modulation (quickly selecting different pieces of the sine and cosine
    maybe 4 times AT LEAST within one cycle of the carrier frequency). It's simpler to use 300 or 1200,
    or DTMF, or Teletype, or Kansas City Standard/ BYTE Standard or even high speed morse code.

    FCC in Region 2 does not regulate that telephone audio "Voice Frequency" band, so turn on your loud hi-fi
    with the BASS up and the TREBLE down, and the volume up to ELEVEN (haha), and then
    connect it to two different grounds for simplex (not simultaneous) transmitting and receiving.
    If you get the buzz from power line radiation then use a delay or notch filter to cancel it out.

    If you receive very high pitched data noises that way, it means the sky is falling! 8O

    Post Edited (VIRAND) : 9/4/2009 5:26:36 AM GMT
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 22,474
    edited 2009-09-04 - 05:33:56
    The 56K modem spec also relies on the fact that beyond the (short) local loop, everything is digital, and it only works at that speed if it's digital all the rest of the way to the server (e.g. via a T1 line or better). If communicating phone to phone (i.e. analog loop -> digital -> analog loop), you will not get 56Kbaud.

    -Phil
    “Perfection is achieved not when there is nothing more to add, but when there is nothing left to take away. -Antoine de Saint-Exupery
  • heaterheater Posts: 3,370
    edited 2009-09-04 - 06:43:09
    Phil, please clarify. I could see that maybe communicating data at 56K in an audio analog line may only work for short distances. But I don't see if my short analog connection to a digital network works at 56K at my end why it can'y work just the same at, say your, end.

    Anyway doesn't 56K rely on compression? I always though that was cheating.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    For me, the past is not over yet.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 22,474
    edited 2009-09-04 - 07:29:40
    heater,

    Everything I know I learned from Wikipedia: en.wikipedia.org/wiki/56_kbit/s_modem. smile.gif

    -Phil
    “Perfection is achieved not when there is nothing more to add, but when there is nothing left to take away. -Antoine de Saint-Exupery
  • dMajodMajo Posts: 774
    edited 2009-09-04 - 07:42:35
    Heater, your so called 56K modem is asymmetrical device when working in that mode (RX@56K, TX@33K). When you are connected to your ISP you have 1 A/D conversion from your line to the telephone company equipment. From here the data are routed/exchanged digitally to/with your ISP. When connecting to a friend your data have 1 A/D conversion from line to telephone central equipment, than they are routed digitally to the destination and converted again (D/A) before entering into your friend's line. So you have double conversion which introduce to much errors in the communication. This is one point, the second is that your modem is asymmetrical so your RX@56K is coming from your friend's TX@33K and vice-versa.

    The telephone copper line bandwitdth should not be a problem, if you think on ADSL speeds, but again here you have only one A/D conversion between your ADSL modem and ISP's DSLAM.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    · Propeller Object Exchange (last Publications / Updates)
    Propeller Object Exchange (last Publications / Updates) --- Oldbitcollector's guest map
    JustForMe
  • heaterheater Posts: 3,370
    edited 2009-09-04 - 08:19:27
    dMajo. I forgot about the asymmetry. That's another "cheat" to make the spec look good in my mind.

    Also what I forgot is that the analog signal from my modem gets converted to a digital voice stream for transport over the telephone network. At that point it must be severely bandwidth limited. Even if the short twisted pair copper out of my house to the exchange can handle the speed that digital voice channel from then on probably does not.

    In my last job my company had designed its own DSL routers 3 ports per box working at 2MB/sec over 3Km or more. so the copper should not be the problem.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    For me, the past is not over yet.
  • Toby SeckshundToby Seckshund Posts: 2,025
    edited 2009-09-04 - 11:50:41
    Copper to copper took all those years of·improvements and "cheats". When you are sticking a couple of copper pipes into the ground... It would be interesting to see·what the·group delay characteristics of an open field (with and without a cow) would·give.

    As Holly is a Lady, She may not be willing to water them in properly.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Style and grace : Nil point
  • edited 2009-10-01 - 04:03:58
    Holly,

    I know you are frugal but I found this new product which has a 40 mile range on Sparkfun and it isn't cheap but you have to be able to do at least 9600 or 115,200 bps.· Here is the link:

    XTend 900 1W RPSMA - 40 Mile Range
    sku: WRL-09411


    ·
  • Cluso99Cluso99 Posts: 15,527
    edited 2009-10-01 - 18:55:40
    Heater: Modems over the switched network (PSTN) are limited to 4KHz bandwidth at the telephone exchange as they are then packed up into blocks. The 56Kbps is the actual speed although this is often not achieved due to line conditions between the house and telephone exchange. Compression is on top of this. However, there is redundency within the 56Kbps. I am not sure of the actual method in 56K but in lower speeds, QAM (Quadrature ??? Modulation) was used where 4 bits (probably more later) were sent simultaneously depicting a quadrant where the signal was. Phase shifting and other methods were used.

    There was a modem called TrailBlazer which used a totally different technique which used multiple sections of the 4KHz bandwith. I think they split it into 7Hz channels and sent each channel slowly (300baud?). It provided about 500 channels and they selected the best group from this. From memory, it used a TMS320 DSP to do this. It was a half duplex system with a tiny back channel.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Links to other interesting threads:

    · Home of the MultiBladeProps: TriBlade,·RamBlade, RetroBlade,·TwinBlade,·SixBlade, website
    · Single Board Computer:·3 Propeller ICs·and a·TriBladeProp board (ZiCog Z80 Emulator)
    · Prop Tools under Development or Completed (Index)
    · Emulators: Micros eg Altair, and Terminals eg VT100 (Index) ZiCog (Z80) , MoCog (6809)
    · Search the Propeller forums·(uses advanced Google search)
    My cruising website is: ·www.bluemagic.biz·· MultiBladeProp is: www.bluemagic.biz/cluso.htm
    My Prop boards: P8XBlade2 , RamBlade , CpuBlade , TriBlade
    P1 Prop OS (also see Sphinx, PropDos, PropCmd, Spinix)
    Website: www.clusos.com
    P1: Tools (Index) , Emulators (Index) , ZiCog (Z80)
    P2: Tools & Code , Tricks & Traps
  • Cluso99Cluso99 Posts: 15,527
    edited 2009-10-01 - 21:37:49
    Holly,

    Aerial farms like that were the norm in the 60's for overseas telecommunications before undersea cables and satellites.

    Then came the huge satellite dishes with cryogenic cooling on the back of the dish for the LNA's (low noise receivers) which is when they discovered microwaves cooked the birds flying in front of them. A few years later they had improved the receivers enough that the receivers could be in a building and refrigeration was no longer required. I saw both at OTC (the phone company) at Ceduna, South Australia in 1971 on one of my training trips. Absolutely fascinating.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Links to other interesting threads:

    · Home of the MultiBladeProps: TriBlade,·RamBlade, RetroBlade,·TwinBlade,·SixBlade, website
    · Single Board Computer:·3 Propeller ICs·and a·TriBladeProp board (ZiCog Z80 Emulator)
    · Prop Tools under Development or Completed (Index)
    · Emulators: Micros eg Altair, and Terminals eg VT100 (Index) ZiCog (Z80) , MoCog (6809)
    · Search the Propeller forums·(uses advanced Google search)
    My cruising website is: ·www.bluemagic.biz·· MultiBladeProp is: www.bluemagic.biz/cluso.htm

    Post Edited (Cluso99) : 10/1/2009 9:44:38 PM GMT
    My Prop boards: P8XBlade2 , RamBlade , CpuBlade , TriBlade
    P1 Prop OS (also see Sphinx, PropDos, PropCmd, Spinix)
    Website: www.clusos.com
    P1: Tools (Index) , Emulators (Index) , ZiCog (Z80)
    P2: Tools & Code , Tricks & Traps
Sign In or Register to comment.