2 Meter Band

Discussion in 'Rocketry Electronics and Software' started by HyperSonic, Nov 12, 2019.

Help Support The Rocketry Forum by donating:

  1. Nov 12, 2019 #1

    HyperSonic

    HyperSonic

    HyperSonic

    Forum Supporter TRF Supporter

    Joined:
    Dec 31, 2016
    Messages:
    163
    Likes Received:
    64
    Here is a list of the 2 meter band. This came from ARRL.org
    2 Meters (144-148 MHz)
    144.00-144.05 EME (CW)
    144.05-144.10 General CW and weak signals
    144.10-144.20 EME and weak-signal SSB
    144.200 National calling frequency
    144.200-144.275 General SSB operation
    144.275-144.300 Propagation beacons
    144.30-144.50 New OSCAR subband
    144.50-144.60 Linear translator inputs
    144.60-144.90 FM repeater inputs
    144.90-145.10 Weak signal and FM simplex (145.01,03,05,07,09 are widely used for packet)
    145.10-145.20 Linear translator outputs
    145.20-145.50 FM repeater outputs
    145.50-145.80 Miscellaneous and experimental modes
    145.80-146.00 OSCAR subband
    146.01-146.37 Repeater inputs
    146.40-146.58 Simplex
    146.52 National Simplex Calling Frequency
    146.61-146.97 Repeater outputs
    147.00-147.39 Repeater outputs
    147.42-147.57 Simplex
    147.60-147.99 Repeater inputs
    Notes: The frequency 146.40 MHz is used in some areas as a repeater input. This band plan has been proposed by the ARRL VHF-UHF Advisory Committee.

    I'm trying to figure out which frequency to use with my BigRedBee 5 watt GPS without P/O anybody. I also want to stay away from the frequency that the repeaters may use. 144.390 MHz is the APRS frequency, but that may have too much traffic on it. The BigRedBee is capable of using any frequency in the 2 meter band. If I just listen to different channels on my radio (Kenwood TH-74A) and see which ones are quiet in Indiana, then I go to Kansas or Nevada to launch my rocket, things will be different over there. Also, what is NEW OSCAR subband? This OSCAR fellow likes to hog up a lot of bandwidth.:) How do you guys and gals determine which frequency is best without P/O anybody? Is that even possible?
     
  2. Nov 12, 2019 #2

    UhClem

    UhClem

    UhClem

    Well-Known Member

    Joined:
    Feb 6, 2009
    Messages:
    1,469
    Likes Received:
    79
    The biggest thing you can do to avoid hogging bandwidth is get your path settings right. Use the wrong one and you could flood any network you reach.

    Do not transmit frequently. Best is something like the Smart Beaconing system used by TinyTrak. Which I see this unit also has. Slow when not moving with fast rate depending on how close you are to digipeaters. If you are close, keep it no faster than 60 seconds.

    You are almost certainly going to be flying a long way from any digipeaters so for the most part you will not cause trouble. That will happen only during the short flight time. 5W is way way too much power and you will have the range to annoy folks far away. I once hit a digi over 100 miles away (in flight only) using 300mW.

    If you wanted to avoid conflicts with the national APRS frequency or other 2m users, 70cm would be the way to go. But on 2m use 144.39MHz and be careful about your settings.


    OSCAR
     
  3. Nov 12, 2019 #3

    RocketDestroyer

    RocketDestroyer

    RocketDestroyer

    Well-Known Member

    Joined:
    Jul 31, 2014
    Messages:
    247
    Likes Received:
    22
    I used 144.90 in the packet radio sub band when I used 2M. I moved up to 435MHz after a few flights for the smaller antennas and less congestion on the band.

    Several years ago there was a W6 station flying balloons from the black rock desert and he used 144.390 with a very short beacon period. I saw packets being spotted from as far away as Vancouver, Canada. I could hear him directly in Boise. To make matters worse he had several balloons flying at one time, all on 144.390 MHz. Needless to say he brought the packet network to a standstill. I would avoid 144.390 MHz if at all possible but that's just me. If you do use 144.390 MHz, I agree with UhClem, don't use a beacon period of less than 60 seconds. What does BRB suggest?
     
  4. Nov 13, 2019 #4

    John Kemker

    John Kemker

    John Kemker

    Forum Supporter TRF Supporter

    Joined:
    Aug 25, 2019
    Messages:
    283
    Likes Received:
    99
    Gender:
    Male
    The Big Red Bee 2m 5W transmitter is an APRS transmitter. Therefore, I would operate it on 144.390MHz, the APRS frequency.

    Don't over-beacon. Don't have more than one transmitter running at the same time. Follow good amateur practice.

    The W6 station? He had transmitters that spent long periods of time at altitude. You shouldn't have anything in the air anywhere near the time a balloon is in the air. Also, he had several running at once. How many us have more than one rocket in the air at the same time? At most, I could see you *maybe* having one transmitter flying and one in your car or on an HT.

    UhClem's advice is solid. So solid, I'd love to see him write a "Rockets and APRS" How-To sticky on the sub-forum. ;-) Whaddya say, UhClem?
     
  5. Nov 14, 2019 #5

    HyperSonic

    HyperSonic

    HyperSonic

    Forum Supporter TRF Supporter

    Joined:
    Dec 31, 2016
    Messages:
    163
    Likes Received:
    64
    Thanks for your help. I will research the path settings to see what my options are and how it effects the signal. Now I remember OSCAR. It's been 3 years or so since I took the test for the technicians license and did not remember him. But I recall reading about satellites with amateur radios onboard. As far as the 5 watts is concerned, I can regulate the incoming voltage from the battery to get any wattage I want. 4 volts input will give me approximately 1 watt output and 7.5 volts input will give me the full 5 watts output. There is also a dBm field in the software that I might be able to tweak. I have to call BigRedBee and ask a bunch of questions. This flight with the big motor(N5800) will be in the air around 7 minutes or so before touch down. You recommend a beacon rate of no more than 60 seconds. That just doesn't seem like enough packets to me. I will surely use the Smart Beaconing option available in the software. Maybe I can program it to a faster beacon rate when it falls below 5000 feet. That way it won't take long from there to hit the ground. I also thought about using different antennas to limit the output power a little, like a rubber duck 3 inch antenna compared to a 15 inch whip.

    I also thought about not using the APRS 144.390 MHz because of all the traffic. If I can find a nice quiet frequency for just around 7 minutes or so, I could use a faster beacon rate without making to many enemies. There might not be any nice quiet frequency's to find!

    This flight will have more than one transmitter at the same time, but not on the same frequency. Pics below. One will be on the 2 meter band, and the other will be on the 70cm band. I don't know if they will play nicely with each other or not, but I intend to find out. 2 totally separate setups with their own power supply's. The BigRedBee and the Telemega for the telemetry. Redundancy is a good thing to have if you don't want to lose anything. I haven't tested the 2 of them together yet, but I plan on it in the near future. Thanks all you guys for your help, and I will let you know how the testing goes when I start.
     
  6. Nov 14, 2019 #6

    HyperSonic

    HyperSonic

    HyperSonic

    Forum Supporter TRF Supporter

    Joined:
    Dec 31, 2016
    Messages:
    163
    Likes Received:
    64
  7. Nov 14, 2019 #7

    John Kemker

    John Kemker

    John Kemker

    Forum Supporter TRF Supporter

    Joined:
    Aug 25, 2019
    Messages:
    283
    Likes Received:
    99
    Gender:
    Male
    Why would you need a faster beacon?

    If you're mainly concerned with finding your rocket, then a once-a-minute beacon is sufficient to tell you where to find it, once it's on the ground. Real-time telemetry of altitude is nice, but is that what you're aiming for? If so, then concentrate on the UHF transmitter for that info. Leave the 2m TX for location and 70cm for telemetry. 70cm can still be used for location, should you need it for backup purposes.

    Nice pics, by the way! You give me ideas!
     
  8. Nov 14, 2019 #8

    HyperSonic

    HyperSonic

    HyperSonic

    Forum Supporter TRF Supporter

    Joined:
    Dec 31, 2016
    Messages:
    163
    Likes Received:
    64
    This is my thinking on things, and I'm not saying it is right or wrong, just my thoughts. This flight will be pushing things a little, well maybe a lot. It sims to about 45K, maybe higher if the weight stays under control. I've already had a telemetrum fail on me once before. It was the only altimeter onboard. Lost the rocket for 3 months before finding it. It was not the altimeters fault. That's where the redundancy comes from. If this flight should shake out the main at 50K, it could come down over 15 miles away. That's where the 5 watt comes from. I have used this 5 watt BigRedBee before, and once it hits the ground, you have to be within 4 or 5 hundred yards from it before you will hear it again. If for some reason the GPS is not valid, it will not send that packet. Thus another 60 seconds goes by. Now its been 2 minutes with no packet. Then say it is close to the ground after another 45 seconds, so I won't get another packet at all. Thus it fell for almost 3 minutes with no packet. The rocket can cover a lot of ground in 3 minutes. The total flight from start to finish is only 7 minutes, so for half of the flight I get no packets.

    I can't even count all the ideas I got from everybody here on this forum. Its like a kick start to my mind! I can't thank them enough for all their help! And a lot of them don't even know how helpful they have been!
     
  9. Nov 19, 2019 #9

    ksaves2

    ksaves2

    ksaves2

    Lifetime Supporter TRF Lifetime Supporter

    Joined:
    Nov 25, 2009
    Messages:
    5,635
    Likes Received:
    110
    I think you could use it on the propagation frequencies,144.275-144.300 Propagation beacons or if you are just going to track locally or 147.42-147.57 Simplex ought to be O.K. Just check to see if the frequency is in use first. You have every right to use the band as anyone else. Once your rocket it down, the signal will likely not carry more than like you state above as long as the rocket isn't in a tree or in high tension wires up in the air. If you have room for a longer antenna on the 2 meter band, that would increase your ground footprint as would a Yagi antenna on the receiver side. Yeah a 3 element Yagi on 2m is a bit large but doable.
     
  10. Nov 20, 2019 #10

    HyperSonic

    HyperSonic

    HyperSonic

    Forum Supporter TRF Supporter

    Joined:
    Dec 31, 2016
    Messages:
    163
    Likes Received:
    64
    I will keep those frequency's in mind when it comes to launch day. You bring up some good points that I didn't think of. Getting stuck in a tree, or on wires above the ground. My thinking was to use enough mAh battery to keep this thing running for days, in case I didn't find it on day one. (don't know what the rules are on how long you can look for a rocket) If I had to come back the next day, it would still be running and since it was on the ground, it wouldn't bother people to far away. But if it's hanging up in the air somewhere, the 5 watt signal will wake up the neighborhood. Not many trees in Argonia or Black Rock, but power lines could be a factor in Kansas. The Smart Beaconing function looks at MPH, and I can adjust the rate accordingly. Is it looking at MPH over ground, or MPH straight up, or both? When the rocket quits moving either vertical or horizontal, I could lengthen the beacon rate say to 60 or 120 seconds in case it's hanging in the air.

    I believe I have enough room in the nose cone to fit a 15 inch whip. The one in the pics above is a 8.5 inch. I must treat each GPS in this rocket as if it is the only one on board, in case one fails for any reason. I have thousands of dollars invested in PePe, and well over 100 hours of my time, so I must do everything I can think of to see that he has what it takes to do what I ask of him. He has become part of the family! I understand that things happen that are out of my control, and I can live with that, but if something should happen to him that was in my control, I will never forgive myself!
     
    GRS likes this.
  11. Nov 20, 2019 #11

    ksaves2

    ksaves2

    ksaves2

    Lifetime Supporter TRF Lifetime Supporter

    Joined:
    Nov 25, 2009
    Messages:
    5,635
    Likes Received:
    110
    As long as you stay off the national 144.390 frequency there shouldn't be a problem. Also if you set the path so you don't clog up the digipeaters on 144.390 you shouldn't have an issue. I see balloon guys sending out packets every 30 to 60 seconds and use a 2-1 path and no body gets too excited. I like to send positions once every 5 seconds to increase the chances of getting position fixes. I do this on 70cm (Beeline GPS) hence no digis are there. On 2 meters I'd simply stay off 144.390 as my rocket hopefully will not end up in the next county. Kurt
     
  12. Nov 22, 2019 #12

    FMarvinS

    FMarvinS

    FMarvinS

    Well-Known Member

    Joined:
    May 27, 2015
    Messages:
    350
    Likes Received:
    36
    Gender:
    Male
    I agree with Kurt. As long as you stay away from 144.390 and local repeater frequencies, you should be ok. For out of state use, you can check the regions repeater frequency listings (available from ARRL). I use 144.800, 144.250, and 144.600 without problems with NMEA transmitted every 5 seconds. One reason to use a similar transmission rate is to acquire enough data to project the flight profile in Google Earth, particularly if the flight duration is less than 5 minutes. With respect to poor signal propagation once the rocket is on the ground, the use of SPOT tracking might be considered. A fellow ham uses spot on his high altitude balloons since he often looses gps reception once the balloon is below a few thousand feet. Spot has been very reliable. If he releases the balloon in an area without local internet capability, he calls friends at home who check the internet spot gps coordinates for him. He then just types in those coordinates on his garmin to walk up to the grounded balloon. The commercial spot units are a bit large and probably will only fit into a 4 inch or larger diameter rocket.

    Fred, L2
    ICBM, S.C.
    KG4YGP
     
  13. Nov 23, 2019 #13

    HyperSonic

    HyperSonic

    HyperSonic

    Forum Supporter TRF Supporter

    Joined:
    Dec 31, 2016
    Messages:
    163
    Likes Received:
    64
    I found this on APRS Paths and Digipeating 101

    Airborne stations above a few thousand feet should ideally use NO path at all, or at the maximum just WIDE2-1 alone. Due to their extended transmit range due to elevation, multiple digipeater hops are not required by airborne stations. Multi-hop paths just add needless congestion on the shared APRS channel in areas hundreds of miles away from the aircraft's own location. NEVER use WIDE1-1 in an airborne path, since this can potentially trigger hundreds of home stations simultaneously over a radius of 150-200 miles.

    Have you ever used no path at all before, or would it be best to just use WIDE2-1?
     
  14. Nov 23, 2019 #14

    FMarvinS

    FMarvinS

    FMarvinS

    Well-Known Member

    Joined:
    May 27, 2015
    Messages:
    350
    Likes Received:
    36
    Gender:
    Male
    I am currently not using paths on the aforementioned non-repeater frequencies utilizing 1 watt and 2 watt APRS transmitters (Byonics) without problems or interference complaints. All launches to date are either at Camden SC or Bayboro NC with waivers maxed between 15 and 17000 feet. From discussions with colleagues that utilize 300 mw output on 2 meters without path settings and not on 144.390, they have tracked their balloons over 50,000 feet without problems until the balloon payload descends below 2000 feet by parachute.

    Fred
     
  15. Nov 24, 2019 #15

    HyperSonic

    HyperSonic

    HyperSonic

    Forum Supporter TRF Supporter

    Joined:
    Dec 31, 2016
    Messages:
    163
    Likes Received:
    64
    Thanks for the help guys. I will try the no path option as I'm going to be the only one tracking this rocket, unless I can get help from someone else at the launch. I will be by myself trying to hold the yagi for the telemega which is hooked up to the laptop and keep track of the Kenwood TH-D74A that's receiving the packets from the BRB. I'm also going to convert my vehicle into a mobile tracking station for the recovery.
     
  16. Nov 26, 2019 #16

    ksaves2

    ksaves2

    ksaves2

    Lifetime Supporter TRF Lifetime Supporter

    Joined:
    Nov 25, 2009
    Messages:
    5,635
    Likes Received:
    110
    As long as one stays off 144.390, doesn't matter what the path statement says. If for some reason you are going to use 144.390 ( I don't know why one would do that for local rocket tracking) then use WIDE2-1.
    I take a small cardboard box that can hold a tablet, H/T or an EggFinder LCD receiver. Cut fingerholes in it and paint the inside with flat black paint. Can hold with one hand and use the Yagi with the other.
    For the 900Mhz stuff, I'll use the vertical dipole or a patch antenna 10 feet up in the air on a pole for dynamic tracking and once loss of signal occurs, switch to a 900Mhz Yagi for the ground recovery. Yagi is not
    necessary for recovery if you can hear the signals coming in. The Yagi will start to return positions sooner than a stock antenna on 900Mhz because it's easy to point at a relatively stationary downed rocket.
    For 70cm or 2 meters the beamwidth of the Yagi is wide enough to be able to use and track dynamically in flight and use for recovery..
    Yeah, Like Fred mentions, it's recommended the balloon guys use 2-1 just so they can get their positions gated to the net just in case they can't directly track. One just goes to aprs.fi and see if the balloon has hit an I-Gate.
    Some years ago, a group was flying a Kenwood D7A(g) in a balloon. They had intestinal fortitude. There was a digipeater with 100 watts and an antenna 100 feet up that was 1200 feet away from my position. I was seeing
    balloons some 400 miles or more away when close to 100k in altitude from that digipeater. I took my Kenwood D7A(g) and sent several messages to the balloon that was flying the other D7. Two weeks later I get an envelope in the mail with
    a CD that contained the onboard camera pictures of the flight and a stamped commemorative tag that flew on the balloon. They got my address from my callsign. That was cool. Kurt
     
  17. Nov 28, 2019 #17

    HyperSonic

    HyperSonic

    HyperSonic

    Forum Supporter TRF Supporter

    Joined:
    Dec 31, 2016
    Messages:
    163
    Likes Received:
    64
    When I tried to delete the default value of WIDE1-1 in the path setting of my BRB, and leave the field blank, the programming software said there must be 7 characters in the path field. I thought about just using 0000000, but then I decided to just use WIDE2-1 and stay off 144.390. The smart beaconing function looks at MPH to adjust the beacon rate. Is that MPH over ground, (horizontal) or vertical as well? Nice trick with the black box. My laptop is unreadable in direct sunlight so I must use a sun shield. People think I'm trying to hide something.

    Is ballooning a hobby, like rocketry, or are they collecting data for other reasons? They sure liked your messages for them to send you some pics. That was pretty cool! Could you post a pic here from a balloon at 100K? I would love to see it. I want to ask you about a good setup for my vehicle using the kenwood TH-D74A and a tri band antenna with a ground plane mounted on conduit on top of the car. Maybe 5 feet above the car. I'll be using a 2 meter BRB, a 1.25 meter RDF, and the 70cm telamega. Would the ground plane help extend the range a little? I can include some pics when I get home. Since the kenwood will give me a bearing and distance to signal, I don't need the yagi as you have stated above. Once the rocket lands, I jump in the car and head to the area where the telemega said it landed at. Then use the kenwood with mobile antenna system to zero in on it. Park car and use handheld antenna with the kenwood and walk right to it. What do you think?

    Happy Thanksgiving to all!!!!
     

Share This Page

Group Builder