Lassen IQ wont' find satellites ?!?

Wireless & IoT
1

Hi,

Just managed to get my Lassen IQ up and running. But…

It won’t find satellites, i tried port 1 with IQ_monitor and it will, send data, recognise SW version and display status (antenna feed = ok).

On port 2 it will send NMEA data and tried to hook it up to

http://www.visualgps.net/VisualGPS/default.htm but it will only show me ‘empty’ NMEA strings.

Yes i did read this thread with the same problem.

http://www.sparkfun.com/cgi-bin/phpbb/v … .php?t=864

I did send a PB to jk to inform me about his solution, but no response yet.

im using the same setup as jk. Lassen IQ with an Ultra-Compact Embedded Antenna for Lassen IQ

Please advice.

2

And you’re outside, right?

-marc

3

Had a similar problem.

Problem was need an unobstructed view of the sky.

Solved by tossing the antenna on top of the roof for a while.

The micro antennas worked after it had updated emphemeris etc using one of the larger antennas.

Wouldn’t update using the micro antenna initally.

I’m in Sydney Australia.

To get more than 3 - 4 sateilites, needed approx 120 degrees of the sky unobstructed (no trees).

4

Yes i am outside.

I will try the roof of my house.

It’s about 12meters high with clear view all around.

I will post results

5

Ceramic side up. Metal shield down.

-Nathan

6

[Click here to see where i live :slight_smile:

Use full zoom to see my street.

It works. But there seems to be a glitch somewhere in the antenna cable or connectors. I have to manipulate the antenna ( twisting the cable to get some reasonable signal strength) to make the IQ lock on. Without twisting the power fluctuates around 2, with the right twist it jumps to 4 to 12 signal strength on some SV’s.

Will investigate more tomorrow.](http://www.mapquest.com/maps/map.adp?searchtype=address&formtype=latlong&latlongtype=decimal&latitude=52.0559&longitude=4.5025)

7

Just have to make sure the cable is securely connected, becareful twisting coax, it doesn’t last as long if its stressed.

8

As testing goes on it looks like sticking the antenna with d-sided tape to the receiver is the problem.

If i lay antenna straight away from the receiver SV signals are strong.

If i put the antenna on the receiver the signalstrength on all SV drops significantly.

9

Up and running GPS and downlink.

see:

http://myuav.blogspot.com

http://www.linxtechnologies.com/index.p … =lr_series

10

Nice!

Pieter - how do you like the Linx RF link? Good distance? Good serial data? Price?

-Nathan

11

Nathan,

It just worked fine. I soldered some cut wirewrap pins to the carriers and made them to fit an inch type proto board. The width pitch is not exactly .10 inch but i managed. As you can reflow it will be much easyer.

The TX was used with an additional amp (allso from Linx) to go for 50mW output.

On the tx I used a 3.3v regulator for the main tx. The amp is directly powered by 5V. The raw rs232 it will accept was inverted and scaled down using a transistor. As i am using a Max232 on the receiving wich inverts i made the transistor invert the signal from rs232 to 3,3v . Inverting on the TX side was not the best thing to do, discuss this more, because during idle the transmitter is allways on. Using a GPS wich sends data all the time this does not matter and my lipo’s will power the tx for more than 20 Hours :slight_smile:

I set all the limiting to 0 to get the full blast out of my tx. As 433Mhz is free to air frequency i dont really care. Some restrictions may apply for others. Read the documentation provided by Linx.

On the RX side I set it up the way the datasheet say’s and used a max232 to condition the output so i can plug it into my laptop.

It works!!!

Antenna’s

On the TX i have a quarterwave dipole

On the RX i have a quarterwave groundplane antenna

The receiver has a nice outpput that will tell you something about signalstrength. We hooked this output up to a digital Fluke and setup the RX at my home. My dad at this end , i called him on the phone, and i was walking down the street wit the TX until he saw the signalstrength drop. I trimmed the TX antenna until signal strength was max again and walked further down the street until it dropped again cut …

The same we did with the RX antenna. If the antennas are matched and if SWR is ok i dont’ know but this methode seems to have worked.

Oh i forgot, i use the LR (Long Range) series.

Data quality is really good at 4800Bd, have not tested other. Only a few nmea packets received are mutilated.

Range is good, at groundlevel we managed about 1000ft i did not bother to go any further. Air to groud will be even better i think.

I did buy my Linx from http://www.simplesolutions-uk.com/linx.htm they are the nearest.

Now is up to you :slight_smile:

Lassen IQ, Linx TX+amp, sma plug and double rs232 output (the lassen has two interfaces) and backup cell

Linx RX, USB and RS232 output, sma plug and testpoint for receiver strength.

For your last question the price is nice:

two sets of TX+amp and RX cost me (converted) $108 including international shipping.

have a look at http://www.rfdigital.com/item.htm?item=rfd24003 for US info.

Later …

12

I’m using linx LR transmitters and receivers too (but at 418 MHz) and I get a lot of bad bytes coming through. I haven’t had a good chance to test range but I made up some very carefully designed boards to use the linx splatch antennae, and microstripped PCB traces between the antennae and the linx modules.

Do you do any sort of encoding / decoding? or are you pumping ‘raw’ rs232 through the modules?

I’m part way through implementing a real manchester encoded link, which should drop my error rate dramatically (rather than the crap manchester I’m using, which I downloaded from somewhere. Does the encoding and decoding but no clock recovery…)

13

Yes i pump raw rs232.

Had really no problem just some sporadic error.

When pumping cyclic data missing a fragment is not such a big problem.

BTW figure out what town i live in :slight_smile:

$GPGLL,5204.2629,N,00426.8649,E,141232.00,A,A*61

$GPVTG,049.0,T,052.4,M,012.0,N,022.2,K,A*2C

$GPGSA,A,3,02,10,13,26,29,2.42,1.60,1.82*04

$GPGSV,3,1,09,02,15,220,34,08,78,141,33,10,71,257,35,13,18,091,34*75

$GPGSV,3,2,09,26,17,277,35,27,54,065,32,28,20,151,32,29,34,280,36*7E

$GPGSV,3,3,09,21,08,334,28,*45

$GPRMC,141232.00,A,5204.2629,N,00426.8649,E,012.0,049.0,260605,03.3,W,A*16

$GPZDA,141233.54,26,06,2005,*64

$GPGGA,141233.00,5204.2649,N,00426.8693,E,1,07,1.28,00016,M,047,M,*6C

$GPGLL,5204.2649,N,00426.8693,E,141233.00,A,A*61

$GPVTG,059.1,T,062.5,M,012.0,N,022.2,K,A*2E

$GPGSA,A,3,08,10,26,29,13,02,28,1.89,1.28,1.38*0F

$GPGSV,3,1,09,02,15,220,31,08,78,141,34,10,71,257,35,13,18,091,33*70

$GPGSV,3,2,09,26,17,277,35,27,54,065,32,28,20,151,32,29,34,280,36*7E

$GPGSV,3,3,09,21,08,334,28,*45

$GPRMC,141233.00,A,5204.2649,N,00426.8693,E,012.0,059.1,260605,03.3,W,A*16

$GPZDA,141234.53,26,06,2005,*64

$GPGGA,141234.00,5204.2668,N,00426.8733,E,1,06,1.55,00019,M,047,M,*67

$GPGLL,5204.2668,N,00426.8733,E,141234.00,A,A*6E

$GPVTG,048.4,T,051.7,M,010.0,N,018.5,K,A*25

$GPGSA,A,3,08,10,13,26,29,02,2.09,1.55,1.39*05

$GPGSV,3,1,09,02,15,220,33,08,78,141,34,10,71,257,34,13,18,091,35*75

$GPGSV,3,2,09,26,17,277,34,27,54,065,31,28,20,151,30,29,34,280,35*7D

$GPGSV,3,3,09,21,08,334,26,*4B

$GPZDA,141235.49,26,06,2005,*6E

$GPGGA,141235.00,5204.2689,N,00426.8763,E,1,04,2.03,00022,M,047,M,L,5204.2689,N,00426.8763,E,141235.00,A,A65$GPVTG,040.0,T,043.3,M,009.9,N,018.3,K,A*29

$GPGSA,A,3,02,10,13,29,3.09,2.03,2.33*01

$GPGSV,3,1,09,02,15,220,35,08,78,141,33,10,71,257,35,13,18,091,34*74

$GPGSV,3,2,09,26,17,277,32,27,54,065,32,28,20,151,32,29,34,280,35*7A

$GPGSV,3,3,09,21,08,334,30,*4C

$GPRMC,141235.00,A,5204.2689,N,00426.8763,E,009.9,040.0,260605,03.3,W,A*18

$GPZDA,141236.54,26,06,2005,*61

$GPGGA,141236.00,5204.2711,N,00426.8795,E,1,07,1.28,00025,M,047,M,*62

$GPGLL,5204.2711,N,00426.8795,E,141236.00,A,A*6F

$GPVTG,046.3,T,049.6,M,010.9,N,020.1,K,A*22

$GPGSA,A,3,02,13,26,29,08,10,28,1.89,1.28,1.38*0F

$GPGSV,3,1,09,02,15,220,34,08,78,141,33,10,71,257,32,13,18,091,35*73

$GPGSV,3,2,09,26,17,277,34,27,54,065,32,28,20,151,33,29,34,280,37*7F

$GPGSV,3,3,09,21,08,334,27,*4A

$GPZDA,141237.49,26,06,2005,*6C

$GPGGA,141237.00,5204.2737,N,00426.8828,E,1,04,1.84,00028,M,047,M,*66

$GPGLL,5204.2737,N,00426.8828,E,141237.00,A,A*63

$GPVTG,040.9,T,044.2,M,011.7,N,021.6,K,A*2E

$GPGSA,A,3,02,13,29,08,2.64,1.84,1.90*04

$GPGSV,3,1,09,02,15,220,35,08,78,141,34,10,71,257,32,13,18,091,34*74

$GPGSV,3,2,09,26,17,277,33,27,54,065,32,28,20,151,30,29,34,280,36*7A

$GPGSV,3,3,09,21,08,334,30,*4C

$GPRMC,141237.00,A,5204.2737,N,00426.8828,E,011.7,040.9,260605,03.3,W,A*10

$GPZDA,141238.52,26,06,2005,*69

$GPGGA,141238.00,5204.2761,N,00426.8860,E,1,06,1.55,00030,M,047,M,*61

$GPGLL,5204.2761,N,00426.8860,E,141238.00,A,A*63

$GPVTG,038.4,T,041.8,M,010.6,N,019.6,K,A*28

$GPGSA,A,3,02,13,29,08,10,26,2.09,1.55,1.39*05

$GPGSV,3,1,09,02,15,220,35,08,78,141,33,10,71,257,33,13,18,091,35*73

$GPGSV,3,2,09,26,17,277,33,27,54,065,32,28,20,151,32,29,34,280,37*79

$GPGSV,3,3,09,21,08,333,27,*4D

$GPRMC,141238.00,A,5204.2761,N,00426.8860,E,010.6,038.4,260605,03.3,W,A*12

$GPZDA,141239.52,26,06,2005,*68

$GPGGA,141239.00,5204.2782,N,00426.8889,E,1,05,1.60,00033,M,047,M,*6C

$GPGLL,5204.2782,N,00426.8889,E,141239.00,A,A*68

$GPVTG,037.0,T,040.3,M,009.7,N,018.0,K,A*27

$GPGSA,A,3,02,10,13,26,29,2.42,1.60,1.82*04

$GPGSV,3,1,09,02,15,220,34,08,78,141,33,10,71,257,34,13,18,091,35*75

$GPGSV,3,2,09,26,17,277,35,27,54,065,32,28,20,151,30,29,34,280,37*7D

14

Pieter-

I think the $GPRMC is saying 52.042N 0.426E, though I can’t really get much more defined than somewhere between Teversham and Halsted, UK with my maps. That doesn’t jive with your profile location though. Hmm.

Regarding the error, it almost looks like you’re dropping a number of messages (six whole ones and few bytes) and coming back in partway thru a $GPRMC, with a scrambled byte being the transition (the *L, which should be a checksum for the $GPGGA, but instead is bungled by what should be the A in the $GPRMC message).

I’ve seen this happen when the serial timing was just a teensy bit off between the transmitter and the receiver of the data, and it only bisbehaved once every few hundred messages in my system. My solution was just to ignore it, since I knew I’d get the right data a second later. The tolerance for RS232 should be +/-8% for the clock, but I’ve found a lot of systems are less forgiving than that.

-dave

15

Oops, I was off by a digit. You’re at 52N 4E, which is Amsterdam if I’m not mistaken. 8)

-dave

16

dpaton:
Oops, I was off by a digit. You’re at 52N 4E, which is Amsterdam if I’m not mistaken. 8)

-dave

here!

http://home.swiftdsl.com.au/~lohagan/Map.jpg

http://home.swiftdsl.com.au/~lohagan/Map2.jpg

17

Close.

But google does decimal degrees.

the gps gives deg, min,sec,decisec

52 04 26 89 N is not equal to 52.042698 deg

04 26 87 63 E is not equal to 04.268763 deg

52.042698 deg = 52 2 33 68 N

04.268763 deg = 04 16 7 55 E

keep on searching … )

18

pvwoerkom:
Close.

But google does decimal degrees.

the gps gives deg, min,sec,decisec

52 04 26 89 N is not equal to 52.042698 deg

04 26 87 63 E is not equal to 04.268763 deg

52.042698 deg = 52 2 33 68 N

04.268763 deg = 04 16 7 55 E

keep on searching … )

Google can do D M S as well…

http://home.swiftdsl.com.au/~lohagan/Map3.jpg

http://home.swiftdsl.com.au/~lohagan/Map4.jpg

19

Indeed, Google Earth does do very nice DMS mapping. It’s a little hard to find when you’ve been drinking however :roll: It also makes GPS messages hard to decode in one’s head 8)

That looks like a beautiful piece of the country.

Did you dig into the serial mismatch any more? I’m a little curious about it, from a purely acedemic standpoint.

-dave

20

Dave,

I think i know what went wrong.

Somethimes the data received suddenly looked like this.

$GPGGA,113921.00,5204.2938,N,00426.8587,E,1,07,1.40,00094,M,047,M,*68
$GPGLL,5204.2938,N,00426.8587,E,113921.00,A,A*61
$GPVTG,246.3,T,249.7,M,024.8,N,046.0,K,A*24
$GPGSA,A,3,02,04,13,20,24,27,08,2.30,1.40,1.82*00
$GPGSV,3,1,10,02,42,297,34,04,À €ÀÀb‚à ÀŠŠšbšŠRºšj D2u2eÅšb’bŠ‚b’šb¢Âb‚²²bš’b’¢b’ÂbŠºªbšºb’ºbšÂbŠ²Êbš²b‚Âb‚ÊbŠÂ²bšªRºšj¤D:AMY±žbšbŠ‚bŠ‚bŠ’b’Ê’b’ÊbŠ²bŠ’b‚ªºbššbbbbbbbbRº5R":AI5
±ÊŠšÊ’Šr‚‚b
±þ’‚¢r’ÊšÂbr±Ã‚¢’²rªºb*±Â’¢rÂb’¢²ršb’²‚²‚ªb‚šršbº±
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