Propagating Prop

g3cwi · 2012-06-24 08:54

Dear all

The large triangular waveform on the attached plot is my Prop coupled to an antenna being received in Italy.

Cheers

Richard

Heater. · 2012-06-24 09:04

I didn't know the Prop had such serious problems with EMI:)

g3cwi · 2012-06-24 09:23

Dreadful EMI problems. That's 800 miles away and all from one single Prop pin waggling about. Imagine the havoc all 32 could cause.

Amazing stuff RF.

Cheers

Richard

Sapieha · 2012-06-24 09:25

Hi.

I assume AT You have some pins don't connected ---> (left-open !) don't any thing connected to them else spare ones not have resistors connected to pull UP them.

In that case that is wanted --- As Propeller pins are build to be sensitive for Analog usage ( Them have internal resistors as NOT sufficient to close that transient's

g3cwi wrote: »

Dear all

The large triangular waveform on the attached plot is my Prop coupled to an antenna being received in Italy.

Cheers

Richard

jazzed · 2012-06-24 09:26

g3cwi wrote: »

Amazing stuff RF.

Indeed.

Can you describe your hardware configuration and/or show us a picture of it?

Phil Pilgrim (PhiPi) · 2012-06-24 09:29

What kind of antenna? How was it coupled? Estimated power output? How are you sure that was you? Enquiring minds want to know! ^TM

-Phil

g3cwi · 2012-06-24 09:35

Phil

Doublet (140 ft top), antenna matching unit. Coupled with a capacitor. I know it's me as I have tried a few different waveforms - and it stops when I turn the prop off !!

I have an accurate microwatt meter so I can measure the power output although it will be the total power including harmonics/spurious etc.

Cheers

Richard

Mike Green · 2012-06-24 09:42

Considering that an I/O pin can source/sink on the order of 40mA, that's 132mW at 3.3V and many QSOs have been done over longer paths with less power than that into a good antenna. Amazing isn't it?

Phil Pilgrim (PhiPi) · 2012-06-24 09:45

I guess the lesson is that, using a good antenna, you can work the world with milliwatts. I don't suppose you sent your call sign with it ...

-Phil

g3cwi · 2012-06-24 09:58

Phil Pilgrim (PhiPi) wrote: »

I guess the lesson is that, using a good antenna, you can work the world with milliwatts. I don't suppose you sent your call sign with it ...

-Phil

Ahh but that's where you are wrong. It sends my callsign in CW at the bottom of each triangle.

CON

  _clkmode = xtal1 + pll16x
  _xinfreq = 5_000_000
  dotrate  = 4000000  '

  LED      = 0 'LED repeater
  TX_Pin   = 4
  
 
VAR
 
  ' counter vars
  long curr_cnt, end_cnt
  long TX_Freq

  word jx, ix, ltr, pntr, letter[60], count, sendltr , strlen
   
OBJ

       
  BEEP   : "synth"  'Sound/rf Driver

PUB Main

  
  Load_Chr_Pointers
  TX_Freq  := 10_140_000
    
Repeat

  repeat TX_Freq From 10_140_000 to 10_140_050 step 1
    BEEP.synth("A", TX_Pin, TX_Freq)
    waitcnt(clkfreq+cnt)
    BEEP.synth("A", TX_Pin, 0)


  repeat TX_Freq From 10_140_050 to 10_140_000 step 1
    BEEP.synth("A", TX_Pin, TX_Freq)
    waitcnt(clkfreq+cnt)
    BEEP.synth("A", TX_Pin, 0)


    
  waitcnt(clkfreq/3+cnt)  
  send("G")
  send("3")
  send("C")
  send("W")
  send("I")
  TX_Freq  := 10_140_000  
  
PUB Send(send_key)  
  pntr:=0
 case send_key
  "A", "a" : pntr:=1 
  "B", "b" : pntr:=2
  "C", "c" : pntr:=3 
  "D", "d" : pntr:=4
  "E", "e" : pntr:=5 
  "F", "f" : pntr:=6
  "G", "g" : pntr:=7 
  "H", "h" : pntr:=8
  "I", "i" : pntr:=9 
  "J", "j" : pntr:=10
  "K", "k" : pntr:=11
  "L", "l" : pntr:=12
  "M", "m" : pntr:=13
  "N", "n" : pntr:=14
  "O", "o" : pntr:=15
  "P", "p" : pntr:=16
  "Q", "q" : pntr:=17
  "R", "r" : pntr:=18
  "S", "s" : pntr:=19
  "T", "t" : pntr:=20
  "U", "u" : pntr:=21
  "V", "v" : pntr:=22
  "W", "w" : pntr:=23
  "X", "x" : pntr:=24
  "Y", "y" : pntr:=25
  "Z", "z" : pntr:=26
  " "      : pntr:=27           
  "1"      : pntr:=28           
  "2"      : pntr:=29           
  "3"      : pntr:=30           
  "4"      : pntr:=31           
  "5"      : pntr:=32           
  "6"      : pntr:=33           
  "7"      : pntr:=34           
  "8"      : pntr:=35           
  "9"      : pntr:=36           
  "0"      : pntr:=37           
  "."      : pntr:=38           
  ","      : pntr:=39           
  "?"      : pntr:=40           
  "+"      : pntr:=41           
  "!"      : pntr:=42           
  "="      : pntr:=43           
  "/"      : pntr:=44           
  ":"      : pntr:=45           
  ";"      : pntr:=46           
  "-"      : pntr:=47           
  "_"      : pntr:=48           
  "("      : pntr:=49           
  ")"      : pntr:=50           
  "'"      : pntr:=51           
  $22      : pntr:=52    ' quotation mark - hexadecimal value      
  "$"      : pntr:=53           
  "&"      : pntr:=54           
  "@"      : pntr:=55
'
'    This portion of the routine reads the string for each letter, number or
'    punctuation and sends the appropriate dots or dashes to the light and
'    sound.
'                                                                                          
 DIRA[LED] := 1
 ix:=0
 ltr:=BYTE[letter[pntr]]
 repeat
  if (ltr=="1")
   Dot
  if (ltr=="2")
   Dash
  ltr:=BYTE[letter[pntr]][++ix]
 until (ltr==0)
 Endletter
 if (send_key == " ")   ' If you have a space, then let another two dot times go by.
  Endletter             ' This increases separation between Morse letters indication
                        ' that an end of word has occurred.

Pri Dot ' This routine sends a dot or "dit" followed by a space the same length 

 BEEP.synth("A", TX_Pin, TX_Freq)
 OUTA[LED] := 1
 waitcnt(CNT + dotrate)
 BEEP.synth("A", TX_Pin, 0)
 OUTA[LED] := 0
 waitcnt(CNT + dotrate)

Pri Dash  'This routine sends a dash or "dah" followed by a space as long as a dot

 BEEP.synth("A", TX_Pin, TX_Freq)
 OUTA[LED] := 1
 waitcnt(CNT + 3 * dotrate)
 BEEP.synth("A", TX_Pin, 0)
 OUTA[LED] := 0
 waitcnt(CNT + dotrate)

Pri EndLetter ' This routine waits for two dots worth of time - no sound, no light
 OUTA[LED] := 0
 waitcnt(CNT + 2 * dotrate)
 
Pri Load_Chr_Pointers

 ' get and store the address of each letter string into the letter array
  ' each letter has a string of letters where 1 equals a dot and 2 equals a dash
  ' each string ends in a zero - since the length of letters in Morse Code
  ' varies (an "e" is a single dot, and a "j" is one dot followed by three dashes)
  ' the address of the start of each string does not occur at a regular spacing
  ' so this array is an array of pointers to the start of each letter.
  letter[0]:=0
  letter[1]:=@A
  letter[2]:=@B
  letter[3]:=@C
  letter[4]:=@D
  letter[5]:=@E
  letter[6]:=@F
  letter[7]:=@G
  letter[8]:=@H
  letter[9]:=@I
  letter[10]:=@J
  letter[11]:=@K
  letter[12]:=@L
  letter[13]:=@M
  letter[14]:=@N
  letter[15]:=@O
  letter[16]:=@P
  letter[17]:=@Q
  letter[18]:=@R
  letter[19]:=@S
  letter[20]:=@T
  letter[21]:=@U
  letter[22]:=@V
  letter[23]:=@W
  letter[24]:=@X
  letter[25]:=@Y
  letter[26]:=@Z
  letter[27]:=@Space
  letter[28]:=@N1
  letter[29]:=@N2
  letter[30]:=@N3
  letter[31]:=@N4
  letter[32]:=@N5
  letter[33]:=@N6
  letter[34]:=@N7
  letter[35]:=@N8
  letter[36]:=@N9
  letter[37]:=@N0
  letter[38]:=@Pperiod
  letter[39]:=@Pcomma
  letter[40]:=@Pquestion
  letter[41]:=@Pplus
  letter[42]:=@Pexclam
  letter[43]:=@Pequals
  letter[44]:=@Pslash
  letter[45]:=@Pcolon
  letter[46]:=@Psemicolon
  letter[47]:=@Phyphen
  letter[48]:=@Punderscore
  letter[49]:=@Popenparen
  letter[50]:=@Pcloseparen
  letter[51]:=@Papostrophe
  letter[52]:=@Pquote
  letter[53]:=@Pdollar
  letter[54]:=@Pampersand
  letter[55]:=@Pat_sign
  
DAT

' Letters in Morse
'
  A     byte  "12",0
  B     byte  "2111",0
  C     byte  "2121",0
  D     byte  "211",0
  E     byte  "1",0
  F     byte  "1121",0
  G     byte  "221",0
  H     byte  "1111",0
  I     byte  "11",0
  J     byte  "1222",0
  K     byte  "212",0
  L     byte  "1211",0
  M     byte  "22",0
  N     byte  "21",0
  O     byte  "222",0
  P     byte  "1221",0
  Q     byte  "2212",0
  R     byte  "121",0
  S     byte  "111",0
  T     byte  "2",0
  U     byte  "112",0
  V     byte  "1112",0
  W     byte  "122",0
  X     byte  "2112",0
  Y     byte  "2122",0
  Z     byte  "2211",0
'
' Numbers in Morse
' 
  N1    byte  "12222",0
  N2    byte  "11222",0
  N3    byte  "11122",0
  N4    byte  "11112",0
  N5    byte  "11111",0
  N6    byte  "21111",0
  N7    byte  "22111",0
  N8    byte  "22211",0
  N9    byte  "22221",0
  N0    byte  "22222",0
'
' Punctuation in Morse
'  
  Pperiod        byte  "121212",0
  Pcomma         byte  "221122",0
  Pquestion      byte  "112211",0
  Pplus          byte  "12121",0
  Pexclam        byte  "212122",0 ' Exclaimation mark
  Pequals        byte  "21112",0  ' Double Dash or Prosign BT
  Pslash         byte  "21121",0
  Pcolon         byte  "222111",0
  Psemicolon     byte  "212121",0
  Phyphen        byte  "211112",0
  Punderscore    byte  "112212",0
  Popenparen     byte  "21221",0  ' Open Parenthesis (
  Pcloseparen    byte  "212212",0 ' Closed Parenthesis )
  Papostrophe    byte  "122221",0
  Pquote         byte  "121121",0 ' Quotation Mark
  Pdollar        byte  "1112112",0 ' Dollar Sign $
  Pampersand     byte  "12111",0 ' Ampersand "&" or Wait
  Pat_sign       byte  "122121",0 'The @ sign        
  Space byte  0,0

Leon · 2012-06-24 10:21

Simple CW transmitters have been built from a single CMOS logic chip, with one gate used for an oscillator, and the others wired in parallel. Here is an example:

http://www.qsl.net/qrp/tx/logi-tx.htm

g3cwi · 2012-06-24 10:45

Using all the pins of the prop it should be easy enough to send pixels to give a 32 x N picture.

Cheers

Richard

Live frequency grabber here:

http://www.stmb.it/grabber/

Phil Pilgrim (PhiPi) · 2012-06-24 11:28

In case you are concerned (and you should be) here's what the spectrum of your program's output looks like (from 0 to 200 MHz):

attachment.php?attachmentid=93717&d=1340562445

attachment.php?attachmentid=93717&d=1340562445

I don't think I'd be connecting such a large antenna to my Propeller. At least if I did, I wouldn't be broadcasting my call sign.

-Phil

g3cwi · 2012-06-24 12:00

Thanks Phil

I'm less concerned than you might imagine as the Propellor is coupled to the antenna via a low pass filter.

Cheers

Richard

Phil Pilgrim (PhiPi) · 2012-06-24 12:53

The lowpass filter will take care of harmonics but not the birdies that result from phase jitter. Here's your signal at 10.140 MHz over a 4 MHz bandwidth, centered on 10 MHz:

attachment.php?attachmentid=93720&d=1340567433

attachment.php?attachmentid=93720&d=1340567433

At least that's better than what it would have been with just the NCO output (no PLL):

attachment.php?attachmentid=93719&d=1340567432

For comparison, here's a 10 MHz signal using just the NCO output:

attachment.php?attachmentid=93718&d=1340567432

And one using PLL:

attachment.php?attachmentid=93721&d=1340567433

This is one case where the PLL actually adds power to the side lobes.

-Phil

Phil Pilgrim (PhiPi) · 2012-06-24 13:03

Things can be much worse, BTW, the farther you deviate from a Prop-friendly frequency. Here's what a Prop PLL-generated carrier at 7.030 MHz (40-meter QRP frequency) looks like:

attachment.php?attachmentid=93722&d=1340568222

attachment.php?attachmentid=93722&d=1340568222

The side lobes are only 25 dB down from the carrier frequency!

To summarize, transmitting directly from the Propeller is not a good idea, due to phase jitter and the birdies it produces.

-Phil

Heater. · 2012-06-24 13:05

Yep, looks like EMI.

g3cwi · 2012-06-24 13:38

Looking good in Nova Scotia:

http://dl.dropbox.co m/u/57842512/Argocaptures/grabber.htm

g3cwi · 2012-06-25 10:21

@PhiPi

Thanks for the plots. I will put my on to my SpecAn soon. While I agree that -25dB spurious is not a great performance, the actual power levels of the spurious are still well down on those that would be within spec for a typical 100W transceiver. Connecting a prop to an HF amplifier would be a bad move but unamplified, and with even a simple filter, it is unlikely to cause problems. I feel that my licence is safe for the moment.

Cheers

Richard

Phil Pilgrim (PhiPi) · 2012-06-25 11:16

Here's how the U.S. FCC regs read:

"§97.307 Emission standards: (d) For transmitters installed after January 1, 2003, the mean power of any spurious emission from a station transmitter or external RF amplifier transmitting on a frequency below 30 MHz must be at least 43 dB below the mean power of the fundamental emission."

The same standard applies whether it's a flea-power QRP transmitter or a 1500W PEP SSB rig.

-Phil

g3cwi · 2012-06-25 11:51

Thanks Phil

I await the extradition papers with interest!

As I said "even [with] a simple filter, it is unlikely to cause problems. I feel that my licence is safe for the moment."

Cheers

Richard

Dave Hein · 2012-06-25 12:12

Phil Pilgrim (PhiPi) wrote: »

Here's how the U.S. FCC regs read:
"§97.307 Emission standards: (d) For transmitters installed after January 1, 2003, the mean power of any spurious emission from a station transmitter or external RF amplifier transmitting on a frequency below 30 MHz must be at least 43 dB below the mean power of the fundamental emission."

Does that apply if the fundamental is above 30 MHz, or is it independent of the frequency of the fundamental?

Phil Pilgrim (PhiPi) · 2012-06-25 12:45

Dave, here's how the regs read:

"§97.307 Emission standards: (e) The mean power of any spurious emission from a station transmitter or external RF power amplifier transmitting on a frequency between 30-225 MHz must be at least 60 dB below the mean power of the fundamental. For a transmitter having a mean power of 25 W or less, the mean power of any spurious emission supplied to the antenna transmission line must not exceed 25 µW and must be at least 40 dB below the mean power of the fundamental emission, but need not be reduced below the power of 10 µW. A transmitter built before April 15, 1977, or first marketed before January 1, 1978, is exempt from this requirement.

They appear to be a lot more stringent above 30 MHz.

-Phil

Mark_T · 2012-06-26 03:16

They are more stringent above 30MHz because in the shortwave band ionospheric propagation variations mean that the main problem is interference from stations thousands of miles away and varies with times of day, solar storms etc - local station interference isn't so crucial. At VHF and above this variability isn't an issue so that local interference is predictable and improving spectral purity means more stations can occupy the airwaves. Its also technically easier to filter low-power high-frequency transmitters as the LC components are less unwieldy.

g3cwi · 2012-06-29 10:15

The trace below shows the prop at 800 miles. Single pin wobbling about and producing the diamonds and triangles at the very bottom of the screen. This weekend I will put the system on a spectrum analyser.

Cheers

Richard

g3cwi · 2012-06-30 02:13

Starting to do some measurements.

The total output at fundamental freq of 10.140MHz (straight from the Prop pin) is +11dBm (Boonton RF Power meter). The useful output at the fundamental frequency will be less of course as the measurement includes the power of the harnonics, spurious etc.

Cheers

Richard

g3cwi · 2012-06-30 02:34

Unfiltered RF output from Propellor on 10.140MHz.

Cheers

Richard

g3cwi · 2012-06-30 04:50

QRSS Code now in OBEX:

http://obex.parallax.com/objects/874/

Cheers

Richard

g3cwi · 2012-07-01 02:14

Update: I have now added slow speed graphics support. See screen shot for what my current 10MHz signal looks like here. The FSK to the right is slow speed Morse code.

If anyone is interested, let me know and I will update the OBEX object.

heers

Richard

PS My transmission received this morning in Norway and Italy.

g3cwi · 2012-07-02 12:43

A new version of the QRSS object is in the OBEX. This includes full fonts and numbers so that it is quick and easy for anyone to configure for their own callsign.

http://obex.parallax.com/objects/874/

Cheers

Richard
G3CWI

Propagating Prop

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