Public Transport Mobile
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ATTENTION! SUNSAT on Rails Operation!
NOTE: The satellite page has been moved here.
Radio on Rails.
Radio on Rails is a fun day/contest run by the Moorabbin and District Radio Club to promote the operation of Amateur Radio from trains and trams. If you're in Melbourne when the event is on, give it a go! Below is a photo of the train mobile participants outside Melbourne's Flinders St Station after the October 10 1999 Radio on Rails day.
From left to right: VK3JED (Tony), VK3YE (Peter), VK3HEM (Daryl), SWL (Craig), VK3ALE (Paul) and VK3KBD (Terry).
And also, a photo from the first Radio on Rails held on April 11, 1999. Again, taken outside Flinders St Station.
From left to right: VK3CAT (Tony), VK3TYD (Hamish, now VK3SB) and VK3JED (Tony).
Introduction:
Not a lot has been written about operating from public transport. I have seen only one other site which mentions the subject so far, written by a local amateur (perhaps only Melburnians are weird enough to attempt it? :) ). Personally, I've been operating from public transport ever since the day after I first got my licence in 1989 (my first QSO was from a train, somewhere between Macedon and Gisborne via the VK3RMM 2 metre repeater). Some highlights include working ZL's (New Zealand) from a train via VK3RGL, which was temporarily linked to New Zealand by a communications satellite and a QSO involving myself and 2 other train mobile stations, and in October 1999, direct contact with the SUNSAT satellite from trains and trams. April 1999 saw my first attempt at contesting from a train or tram, during the Radio on Rails day on April 11, which put past experience and gear to the test. :-) While I didn't win this time around, the contest validated a lot of the experience I've outlined below. My total experience would cover over 1000 hours on public transport, mainly within the suburbs and west of Melbourne, Australia.
Equipment.
I used to use an Alinco DJ500T dual band handheld until recently, which allowed 2m and 70cm to be covered. This radio only outputs 2 watts from the battery pack. A 5 watt radio, battery combination would be more suitable, as repeaters and base/mobile stations tend to run more power than this. The battery pack had been upgraded to 1.3 AH, by replacing the original NiCd cells with high capacity NiMH cells, which gave about 2 hours ragchewing time (actual time participating in a QSO). One excellent feature of this radio is it had extremely low standby current drain - I have accidentally left it on for over 24 hours and found it still full of life. Also, it had an attenuator built in, which was handy when travelling close to the city, as it significantly reduces overload from pagers and other out of band transmitters.
I have since upgraded to an Icom IC-T81A, which is the new quad band handheld. This new unit offers the additional bands, 6 metres and 23cm, more transmitter power (5 watts on 6, 2 and 70, 1 watt on 23cm, when using the 9.6V battery), a more sensitive receiver, scanning and wide band receive (from 50 MHz to 999 MHz with a gap around 230-300 MHz).
Also, I have a Standard C58 all mode 2m transceiver. This is a "transportable" unit with internal batteries, much like the Yaesu FT-290R. This radio offers the possibility of "train DX" using SSB, and a receiver which is much more resistant to pager interference that the more modern FM rigs, a problem which plagues the 2m band in Australian cities. The paging transmitters operate between 148 and 150 MHz and have an EIRP of up to 1000 watts. This makes 2m operation in the city unpleasent, difficult, or sometimes even impossible, unless you have a receiver designed to handle this hostile environment.
For extended periods of operation, a 12V 6.5 AH gell cell is used to provide power. When the gell cell is in use, the DC power distribution is provided by a home made loom which utilises connectors salvaged from dead computer CPU fans.
Photo of Icom IC-T81A and Alinco DJ-500T
Left - Icom IC-T81A. Right - Alinco DJ-500T.
For antennas, I have 3 which I use regularly. The standard rubber duck, which is compact, but only good for strong signal areas. The typical rubber duck supplied with handhelds is generally inadequate for public transport mobile work, so other antennas are needed.
On 2 metres, I use a home made 1/4 wave antenna. A standard 1/4 wave antenna is a poor performer, because the handheld makes a poor groundplane for it to work against. To solve this problem, I added a counterpoise, to act as an artificial ground. During operation, this simply hangs down (it need not be completely straight - as long as it's kept more than 15-20 cm from the body or metallic objects, the antenna works well). Performance when standing out in the open is equivalent to a commercially built 1/2 wave or 5/8 wave antenna (actually better than some models). Within the confines of a train, tram or bus, it is usually better, both from a convenience and R.F. point of view. This antenna is also telescopic, which is handy for when I'm not using the radio, or switch to another band.
For 70cm, I use a commercially available UHF CB 1/2 wave antenna, which has been extended to retune it to 70cm by stuffing in a piece of RG58 coax with the braid exposed so it will make contact with the braid of the antenna element. In practice, counterpoises were found to be less effective than on 2m, so a ground independent antenna like the one I use is most effective for this band.
Both the 2m and 70cm antennas have also proved effective during the John Moyle Field Day contest, where a few stations commented on my "good" signal for a handheld station (No, I wasn't on a train there, just standing on a hilltop :-) ).
Here's a photo of the high performance antennas I use on 2m and 70cm.
From left to right: Modified UHF CB whip (70cm), 2m 1/4 wave with counterpoise (the best 2m antenna), "ScanDucky" scanning whip (good for 2m), and commercially made dual band antenna (compromise for 2m/70cm).
It's worth commenting on the range of commercially available antennas, and why I don't use them. The 2m 1/2 wave and 5/8 wave ones do perform well in the open, but on public transport, the 5/8 wave antennas are simply too long to be effective, they extend too close to overhead metalwork, which reduces their efficiency drastically. 1/2 wave antennas are OK, though suffer from this effect to a lesser degree. I'd recommend homebrewing on 2m, otherwise use a 1/2 wave (and don't wave it around too much on a crowded train! :) ). Recently, another unlikely contender has proved to be a very capable antenna on 2 metres. Mobile One manufactures a scanner antenna called the "Scan Ducky", which is a solidly built wideband antenna designed for handheld scanning receivers. By a lucky coincidence, this antenna also performs very well on 2 metres, almost as well as the 1/4 wave counterpoise. I use the ScanDucky when I want something a little shorter or "better looking" and can afford the slight loss in performance (it goes better with a collar and tie! :-) ).
There is much less choice for 70, in the commercially available stakes. If a 1/2 wave is available, buy it, though I haven't seen one in the stores, hence my conversion of the UHF CB antenna. A small (say 1/2 wave over 1/2 wave) collinear might be interesting to try as well. As for the dual band antennas, I did try one, which was supposed to have superior gain, and was a little less than a 1/4 wave on 2m. However, the performance wasn't much better than the standard rubber ducks for either band, and the counterpoise didn't raise its 2m performance much. That antenna only gets occasional use on the scanner for listening to 6m or broadcast FM stations (its wideband performance is better than the dedicated scanning whips!). I haven't tried the longer telescopic dual banders, but suspect they suffer from the problems associated with their physical size in confined spaces, like the 2m telescopic whips.
6m and 23cm are definitely home brew territory, though a 2 metre 5/8 wave should also work well on 6m (but with the space problems these antennas have on 2m). I have discovered that old mobile phone antennas can be useful for 23cm. I purchased an old analogue phone antenna, complete with SMA connector for $1.00. Even unmodified, this antenna outperformed the standard rubber duck by a significant margin. I have since pruned the antenna down to retune it from 870 MHz to 1290 MHz. I also have a number of ex mobile phone 1/2 wave antennas which could be interesting to play with on 23cm, but need to make an adapter for their non standard connectors.
I haven't yet built any specialised antennas for 6m , but I do have some ideas on the drawing board. For 6m, I have designed a ground independent (1/2 wave resonant) and a more conventional 1/4 wave resonant helical. Both designs are 0.5 metres long, suitable for use within confined spaces.
Peter, VK3YE, in his article finds a dipole stuck to the window effective for 2m. I prefer not to stick antennas onto windows myself, it attracts attention, and limits mobility (which can be a concern when trying to find the best seat, or when you have to jostle your way to the door on a crowded peak hour train before your station!). Give this a try too, Peter says it's effective.
Other bands - Well, I can now offer something more than educated guesses here finally! :-) 6 metres inside a vehicle is a write off. While the VK3RMS repeater more often than not pegs the S meter on the HT, when inside a train or tram the signal drops to S1-3, and the repeaters are generally inaccessible. I'd estimate the loss at 6-9 S points (allowing the the obviously out of calibration S meter on the Icom! :-) ). My theory is that at a wavelength of 6 metres, the apertures (windows, etc) of a train or tram are too small to allow the signal through, and the vehicle begins to approximate a Faraday cage. This falls in line with previous experience on 27 MHz CB, where the attenuation from the carriages was extremely severe.
At the other end of the spectrum, 23cm shows a lot of promise and I have had a few contacts within the first few days of operation here. On a tram, the signal inside is almost as strong as the signal outside, with only a slight loss as you move away from the windows. The 23cm signals are also strong near the doors of a train, but show signs of falling off when one moves away from the door. I suspect the dreaded window tinting has a severe effect up here. Unfortunately, 23cm propagation isn't as "mobile friendly" as the lower bands, so signals can drop out when going through cuttings or when there's a large building between the repeater (or other station) and the train/tram. In Melbourne, the VK3RCC repeater on 1273.100 MHz works well within 10km of the city. I noticed that the 23cm devices don't seem to be as powerful as their 70cm counterparts. However, excellent copy can be achieved with signals that barely register on the S meter - something others have noticed on 23cm.
What's next? I still have to do some antenna experimentation on 6m and 23cm, and bring these bands up to the same standard that 2m and 70cm enjoy (But will they let me install external whips for 6m? :) ). I am also looking into the possibility of 2m SSB work as another train mobile experiment. I do know of one other SSB capable train mobile station, so perhaps we'll try something like train-train DX, taking advantage of SSB's higher efficiency.
Preparation:
How much you prepare for public transport operation depends on the trip. For a routine trip, like my daily work run, it's simply a case of grabbing the radio, antennas and walking down to the tram stop (and don't forget to buy a ticket! :) ). For longer journeys, or unfamiliar areas, you may want to consider:
Repeater listings - You will spend most of your time using repeaters, so knowing where they are is an advantage. Try and find out the exact sites and terrain between the repeaters and public transport route you will be taking.
A map -Preferably with topographic information, to help determine likely propagation conditions along the route, and to mark the repeater locations on.
Log book - Record not only contacts, but repeaters accessed and signal conditions/quality. This information will help you to assess conditions on future journeys in unfamiliar areas. It is worth plotting the results on the map after returning home, to get an overall picture. Having said that, I rely on long term memory for this, but some people may find using a map and log book easier. Develop your own style here. :-)
Operating Techniques:
Operating from public transport, where there is limited power, antenna space and no control over the vehicle's motion works best if you use a few techniques. Firstly, get to know your route. No, not the stations (though that's important, of course :) ), but propagation conditions along the route. If it's a familiar and regular route, it's worth listening when not in a QSO, to get a feel for what conditions are like. With practice, you will get to know what sort of received signal from a repeater you need to be able to transmit into it and be heard. For unfamiliar routes, this is where the map comes in. You can mark off the repeaters and use experience gained from more regular routes (effects of hills, valleys, buildings, etc) to make an estimate of the areas where you will be able to access each repeater. Of course, there will be local features (e.g. cuttings) which may not be picked up on the map, but it all helps. Similarly, get to know the repeaters. Some will be 'deaf', others will happily retransmit very weak signals. Of course, on simplex (e.g. calling CQ on 146.500), there's always the pot luck element.
When in a QSO, there are a few things to watch out for. Firstly, try not to start a QSO in a marginal area, unless you know the route well (and know it will improve). You might find yourself "dropping off the side" halfway through your over. Murphy seems to take delight in pulling this trick! Similarly, if the train, tram or bus is pulling into a stop, and the signal has been relatively weak or uncertain, try and finish your over before it comes to a stop. You may end up stopping in a null and not know it until you release the button. When in a group, it's sometimes effective to change the order (e.g. pass it onto someone else when you know you're going into a bad area and getting them to pass it back), to avoid transmitting while in a poor area. Often, you will still be able to hear the QSO, and hopefully you'll be within range when it's your turn (this can where passing it to someone who takes long overs can be handy! :) ). I managed to participate in QSOs in marginal areas by using this technique. Now, I simply use better antennas. :-)
Finally, a comment on selecting your seat. If you're able to choose a seat, the general rule is to choose a window seat on the side of the vehicle the repeaters or other amateurs will be on. On a long trip, this may mean swapping seats occasionally. However, each vehicle has its own quirks, and I can offer a few more hints for those taking on Melbourne's public transport system.
Trains:
Comeng suburban electric trains. These are unfortunately, despite their huge windows, rather like a Faraday cage There are few good spots, and the best I can suggest is to choose either a window seat, or stand by the door. Avoid areas between the windows like the plague, especially the pillars next to the doors. You will get lousy signals. You will need good antennas to get any reasonable range out of these trains. 70cm appears to be worse affected than 2m. However, I have recently discovered that it is sometimes possible to obtain good signal strength on 70cm in these trains by sitting near the window on the _opposite_ side of the train to the station or repeater you're trying to work! More investigation into this phenomenon is needed, but results can be quite good, almost as good as the "best case" of the older silver trains below. It appears to be localised to within 20-30cm of the "opposite side" window. No enhanced signals occur on the side facing the other amateur station.
The older silver trains are much better. The seat I'd recommend is in any of the extreme corners, next to the window (that's the corner seats where you face either forwards or backwards, not the sideways ones). These positions seem to have a much stronger signal, even on the side opposite the repeater or station you're working. (Perhaps the corner of the bodywork acts like a corner reflector, capturing stray R.F. bouncing around the inside of the carriage?). From these prime seats, even a standard rubber duck will work well. This is a good way for a beginner to try out train mobile.
As for V/Line trains, the older "Harris" cars (common on Bacchus Marsh, Kyneton, Seymour, Leongatha lines) are pretty poor, but unlike the Comeng trains, you can get a very good signal standing by the door. If working "train DX" is your goal, it's worth standing for the trip. On these trains, 70cm is the choice band, with generally stronger signals here than on 2m. It appears that the doorway allows the shorter wavelength to pass through more easily.
The carriages used on the longer routes are excellent for radio work. Simply sit beside the large window in a comfortable seat and enjoy the QSOs (and scenery, if the bands are quiet :) ). I have little experience with the new "Sprinter" trains, but these look as though they may be OK for radio. It was on a train originating from Bendigo that I managed the 50-80 km trip into VK3RGL to work the ZLs.
In December 1999, I finally got my wish to try Amateur Radio from Sydney's "Tangara" double decker trains. From the top level, propagation is excellent, with nittle noticeable attenuation of the signal. Despite the tinting, the large windows which "wrap around" overhead seem to offer a good path. The layout of these trains makes them potentially the best carriages for working satellites, due to their excellent overhead visibility. Maybe I'll get to work a satellite from a Sydney train in 2000. :-)
In general, where there's tinted windows, there's likely to be trouble, and you'll have to look more creatively for the best position on the train. Large clear windows offer the best signals. Future testing on more bands will help determine how the effect of each component on the signal varies with frequency.
Trams and buses: These seem to have fewer complexities than trains. In general, trams are poorer than buses, and the best bet is the usual window seat. If the tram will be heading towards or away from the direction you'll be working, try grabbing the seat nearest the end, but on the opposite side of the tram to the driver's cage. You'll have window space close by on 2 sides to take advantage of. However, the major problem with trams is that they are extremely noisy on the lower bands (6m, 2m), with noise levels of S5 - S9 sometimes observed on 2m. 70cm and 23cm, where noise isn't a problem are good bands for trams. Buses tend to be fairly good, and a window seat away from side pillars will generally give good results. Coaches may give better results than other buses, because of their height. The biggest problem with buses is that they tend to turn more frequently than trains or trams, making working in marginal areas a bit tricky as the bus changes direction.
With 4 bands of data becoming available, I'm working on building a set of "vehicle profiles", for which early trends are already apparent. All land based public transport (except some relatively rare non metallic vehicles) consist basically of a metal shell interrupted by rows of openings which vary in dimension from 1 metre to 2.5 metres. This gives rise to a basic frequency response which is fairly flat in the mid VHF-UHF range, but sharply cuts off below a critical frequency, where the Faraday cage effect takes over. This "cut off" frequency is between 54 and 90 MHz (6m is no go, but FM broadcast radio works fine) for most vehicles. The actual cut off frequency is a function of window size (On Harris trains, the cut off frequency is closer to 150 MHz, due to smaller windows, except near the doors). Superimposed on this basic "high pass" response are absorption due to passengers, which can affect the UHF region to some extent, though in practice, the limitations crowded trains impose on antenna positioning have more effect than the absorption itself. Tinted windows limit performance in the UHF spectrum, turning the basic "high pass" characteristics of the vehicle into more of a "band pass", which favours the 2 metre band above all others.
Tram stops and stations - These are like working from any portable location, but it's worth mentioning that again Murphy has his fun. Platforms can sometimes make for improved propagation, Essendon Station, which is a metre or so above road level is a classic example. It's possible to get a decent signal into VK3RSE, 30 km away with 250 mW. However, just around the corner at the tram stop is a real dog of a location for this repeater. There, like the station, the repeater puts in a strong signal, but it is _very_ difficult to access the repeater on a standard rubber duck while stationary. The propagation is _very_ one way, heavily favouring the output frequency on a consistent basis. Even worse, the constant movement of traffic makes it impossible to find a good area and stay there, the signals move around with passing traffic. The only way I conquered this location was with the 1/2 wave antenna, and even that strikes the odd null occasionally. In the inner suburbs, the high gain antennas used for public transport can work against you, by pulling in all the R.F. crud that is around the city. On 2 metres, this is typically pagers. On 70, commercial voice and data traffic from the nearby base stations, taxis, police, etc. This is where the attenuator comes into its own, it makes a huge improvement in received signal quality under these conditions. The other technique that can work well on 2 metres, is to make your antenna telescopic, like mine. By withdrawing the antenna on receive, _and_ using the attenuator, you will almost eliminate pager interference. Just watch you don't overdo it, otherwise the repeater or other station might disappear too! Oh, and remember to extend the antenna before transmitting, of course. :-)
Stares, strange looks and comments:
It's worth a light hearted comment about other passengers' reactions to someone yakking away into a radio in their presence. Most people simply won't pay attention. Others may make a comment or take a another look. One of the funniest incidents was during the infamous "scratch ticket" era of Melbourne's public transport. I hopped onto the Kyneton bound train at St Albans, with radio in hand, and started tuning around. There were a couple of teenage boys who looked up every now and then, then one of them came up and asked "Are you an inspector"? I told them no, and the conversation turned to the radio, so I filled them in on what it was all about. At that point they said "Damn, we scratched our tickets because we thought you were a cop!!!" :-) Amateur radio helping out the public transport system? :-) After that, we often met and chatted on the train of an evening.
Another incident last year happened at the usual tram stop. I arrived to find a tram derailed near the stop, and people waiting around. After trying the repeater, to see if anyone was going past (no one was), a bus pulled up in an unusual place, and I guessed that it had stopped to pick us up. As I approached the bus, the driver yelled out "Tell the people to take this bus". Seems he saw the radio and thought I was a tram worker! Being mistaken for officials will be one of the side effects of operating from public transport. It's not a problem, but can be amusing at times. :-)
Well, I hope I've generated a little interest, and maybe if you're nearby, I might hear you on VK3RSE one morning. Public transport need not be a drag, it can instead become an interesting place to use a radio, and be one way of combining a necessity with a hobby, and enjoying radio without sacrificing your home life and responsibilities. On longer trips, it might be just the cure for a boring trip with boring passengers. If no one on the train will talk, I'll find someone else outside to talk to! :-)
Offbeat, unusual or plain silly? :-)
This section is for the more unusual operating techniques I've tried on public transport.
Anyone else got some more unusual operating situations?
Other related sites:
Peter, VK3YE's article "Transmitting from Public Transport", from the WIA's Novice Notes Online series of articles, and published in Amateur Radio, December 1998.
Leighton, VK3HLJ's Radio on Rails page.
Jan-Martin, DL2LFH provides a European perspective on Railway Mobile Operation. Includes links to several major train "DXpeditions".
Patrick, KF6OTP operates train mobile in San Mateo in California, USA.
If you travel on an underground rail system, why not try out for the Tube Award!
Share your experiences!
Have you operated from public transport, or even better, have you written about your experiences? If you answered yes to either question, I would like to hear from you. The links above are the only sites in the world that I know of which deal with the subject. If you have a relevant site that I've missed, please let me know so I can add a link. You can send me an email by clicking on the link below.