Your readability is less than 1

[cscotthendry]

I've been thinking about the quality of some radio comms, for some time as I've heard some shocking radios while out flying. Some have so much noise, the transmission is unintelligible. Some have such poor strength that the transmission is inaudible even when nearby. I usually tell these people that their transmission was unreadable, but rarely get any responses from them.

 

I've thought about setting up a repeater on an unused frequency that pilots could transmit to, and the repeater would re-transmit what they had sent. This would give them an indication of how their radio is performing.

 

I know that it is normal to do a radio check before flying and that there is always the option of calling the area controller for a check, but at the field where I fly, often I'm the only one there and I'd rather not bother a busy controller for a radio check while he's handling airliners.

 

Thoughts? Comments?

 

BTW just to head off the "but what about your radio...?" I might add that I'm pretty sure it's not my radio as I have recordings of received transmissions from my aircraft and when I ask for radio checks, I usually get 5's from ground and other airborne recievers.

 

 

[facthunter]

All good thoughts. IF you feel you need a radio check a call to your "Busy" ATC person when he doesn't appear to be too busy should not bother him. I'm 'sure he will cope with the pressure. I have made an all stations call and got an amateur with a hand held, to reply, which is interesting. I agree that many radios are appalling. Nev

 

 

[Compulsion]

No offense to anyone but Gliders seem to have very poor radio transmissions and use. I can only speak for my flying area.

 

 

[djpacro]

I have noticed that too, Compulsion, batteries flat at the end of a long flight. Was talking to a friend working on his glider only yesterday - fitting three batteries into it so he can switch over to maintain the power for his radio.

 

 

[facthunter]

This one has a ticket. I found out after some time, who it was. There are a few people around aerodromes who monitor calls out of interest. I believe in the need to do radio check calls. I have gone into busy circuits and made up to 4 calls and no-one acknowledges ( They don't have to ) but at that stage I start to wonder if I am getting out and request acknowledgement .Nev

 

 

[Bryon]

I have had occasions in the Jab when someone has told me that my transmissions are crap and other times when I have done a check they are 5s

 

My thoughts are that the Jab has the antennae mounted underneath the fuselage. Wouldnt it be better to mount the antenna on the top for maximum radiation with no fear of masking by the fuselage, or better still have an antenna both top and bottom?

 

Any thoughts???

 

 

[Kyle Communications]

Hi Scott

 

Actually I like the idea of a "simplex repeater" for testing radio transmissions. I too can not believe how many crap radio transmissions are in the YCAB area and outer parts that I fly in. For those who don't know a simplex repeater is a radio that transmits and receives on the same frequency not like a normal duplex repeater which receives a radio transmission on one frequency then passes this to a different frequency for transmission out in real time hence the term duplex...like on a UHF CB with the duplex button.

 

The simplex repeater receives a transmission and records this into ram ( computer storage chips like in your computer) it does this when the squelch opens on the receiver it starts to record what it hears then when the squelch closes it then begins to clock out the recorded voice the same as what it was recorded like. This way you can hear back what your transmission is like. I think it is a great idea. I will get hold of the ACMA and see what the legalities are and licencing fees and see what I can do about putting one up in the YCAB area. I am not far from YCAB and could site one here or even better site it up at my commercial repeater site at Ocean View which will give it a huge coverage. We would have to have a specifically allocated frequency for this type of use hence the ACMA rules and the government likes to extract money for any radio comms licensing.

 

I will make some enquires next week and see what they say.

 

 

[Kyle Communications]

Hi Byron

 

My aviation antenna and the UHF cb antenna are both mounted UNDER the nose section of my Savannah. The theory behind this is to cover maximum USABLE radio coverage. The angle of radiation of antennas mounted on top of a ground plane is upwards and this angle varies with the different types and shapes of the antennas. While the aircraft is on the ground your range is reduced obviously reduced as the antenna is very close to the ground but as soon as you takeoff the range dramatically increases and at the heights we fly at the coverage is probably the best you can have. if the antenna is monted on the top of your aircraft yeas you can talk very well from the ground and at lower heights but then once you start going up in height the aircraft starts to block the little radiation you have going in the downwards direction. Certainly the jet jockies will hear you at 30,000 feet but the guys on the ground or at low level under would struggle to hear you.

 

An antenna on the top and bottom will make a huge difference but then you are splitting your power in half to do this and this would probably be ok anyway as when you are up high you dont really need too much power anyway as radio signals go in parallel lines of force so height is might and the only thing that will give you path loss is the atmosphere and mountains etc. but your signal would be going out into space as it goes past the curvature of the earth.

 

I elected to go underneath on my aircraft due to my 30 years in radio experience and so far have had reports that my radio "gets out" extremely well and no one has not answered me when either on the ground or in the air. if I can hear them I can speak to them and that really is what you are aiming for

 

Mark

 

 

[Kyle Communications]

You can see the Comant 121 aviation antenna on the pax side and the UHF small end fed dipole on the pilot side underneath at the front

 

 

 

[cscotthendry]

Kyle:

 

Just out of interest how would a dual antenna configuration work? If say, one antenna is 1/4 wavelength, would that make two antennas effectively a 1/2 wavelength antenna? What about the distance between them? Would that change the effective antenna size? Also how would the the VSWR be affected? I can think of a hundred other questions regarding phase interference etc, but I'll leave those for another time. Maybe over a beer or two one day. BTW I have seen antenna switchers on military aircraft, but don't recall a dual antenna installation where both antennas are active at the same time. If it's feasible, I might consider it on my airplane as a test.

 

I fly out of Watts bridge and would benefit from a repeater if you put one up. Let me know if I can help (ex avionics tech USAF).

 

 

[Kyle Communications]

Hi Scott

 

The issue with dual antennas really is one of phasing. As you know you can get cancellation of signal if they appear 180 deg out of phase. To make it operate is actually not that hard a splitter combiner or phasing harness is needed and that is quite simple actually. Off the main 50 ohm feed you put a tee piece probably bnc for weight and you need 2 of 1/4 lengths of 75 ohm coax with calculated velocity factor for the 75 ohm and its literally as simple as that this is the splitter which basically allows 2 of 50 ohn antennas in parallel which is 25 ohms to be matched to the original 50 ohms at the radio. The radio needs to look at 50 ohms so if you just split it with 50 ohm coax you would have a bad mismatch to the antennas. Ideally both antennas would be directly underneath each other one facing up and the other facing down and a ground plane on the both the same size not easily done on a lot of aircraft as you need around 600mm square of ground plane to have the best radiation pattern and efficiency

 

I have looked up the Simplex repeater module and it is still available and I have a spare IC-A200 here but I actually want to put that up at my farm. I just remembered while writing this I have a brand spanking old Tait T373 airband crystal locked radio here that I can get a crystal made for the frequency if I can get this through the ACMA and will fit the simplex module internally nicely so it just requires the 12 volts already at the repeater site and another antenna. The antenna can just go on the top of our shipping container so literally would take 30 mins to install the whole thing. All depends on what the ACMA says. They banned the simplex repeaters on UHF CB when they appeared about 10 years ago but if I can put up a good case I might be able to at least get a test period for it

 

Mark

 

 

[trevorp]

I have noticed that too, Compulsion, batteries flat at the end of a long flight. Was talking to a friend working on his glider only yesterday - fitting three batteries into it so he can switch over to maintain the power for his radio.

Gliders [sailplanes] should have some sort of solar panel , surely that should be lighter than 2 extra batteries.

 

 

[Herm]

Just use a dipole antenna as the radiation pattern radiates from top and bottom. They also do not need a ground plane. My Jabiru has a crude one fitted in the fin that works pretty well with good SWR readings. This type of antenna is the best IMO and I have been supplying them for aircraft for 7 years now. Have use them in lots of wood aircraft and the RAAF has also used them in some of thier projects... I am one of those guys that makes gear for others and yet still has rubbish fitted to his own aircraft...LOL...

 

If you aircraft has the room for a 1/2 wave dipole, you won't be sorry fitting one and thier are some feat options available. So many people get hung up on polerization, but an aircraft is always banking and pitching that is always changing that. Also others are doing the same and with a vast variance in thier antenna systems.

 

Mardy

 

 

[Kyle Communications]

1.25 mtrs for a halfwave dipole centred on 120 mhz I couldn't fit that in mine anyway its all metal.what sort of match are you using?

 

 

[Herm]

1.25 mtrs for a halfwave dipole centred on 120 mhz I couldn't fit that in mine anyway its all metal.what sort of match are you using?

I make my own matching unit that fits between the dipoles. It is all mounted in a waterproof housing of polycarbonate so it won't short out on metal mounts. They were originally made for king post aircraft but have been used in all sorts of other applications.. Anyway I don't want to mention anymore as This forum is not an advertising platform, but wanted to give my opinion on antenna usage type based on my experience.

 

Mardy

 

 

[frank marriott]

I realise come posts are toung in cheek but just be clear on aircraft speak - there is only 5 levels:

 

1. Unreadable

 

2. Readable now and then

 

3. Readable but with difficulty

 

4. Readable

 

5. Perfectly readabel.

 

Some people use 5s. which would refer to the electronic terms of strength x clarity.

 

Some use 10 which I guess is a combination of the 5 by 5.

 

Not a big point but might be interesting to some who either didn't know or have forgotten. Helps if everyone is using the same yard stick.

 

FrankM

 

 

[eightyknots]

I realise come posts are toung in cheek but just be clear on aircraft speak - there is only 5 levels:1. Unreadable

 

2. Readable now and then

 

3. Readable but with difficulty

 

4. Readable

 

5. Perfectly readabel.

 

Some people use 5s. which would refer to the electronic terms of strength x clarity.

 

Some use 10 which I guess is a combination of the 5 by 5.

 

Not a big point but might be interesting to some who either didn't know or have forgotten. Helps if everyone is using the same yard stick.

 

FrankM

I'm sure the thread title is tongue in cheek . You simply cannot have less than 1 (unreadable). Just like there is no Year Zero because the calendar started from Year 1.

 

 

[Gentreau]

1.25 mtrs for a halfwave dipole centred on 120 mhz I couldn't fit that in mine anyway its all metal.what sort of match are you using?

There is a guy in South Africa who makes a V shaped dipole which is claimed to work very well and the shape helps with the installation.

 

It has the same name as a certain latex covered object with an internal unbalanced electric motor which I understand is popular with the laydeez :)

 

 

[Mick]

Question: You arrive at a busy CTAF® say in a regional city, not long before last light only to discover that other traffic ( RPT's ) in the circuit are not reading your calls at all. You do not have enough light left to go elsewhere ( non radio CTAF ) and there is no coverage to pick up a transponder switched to 7600 to indicate radio failure. What do you do?

 

 

[dazza 38]

There is a guy in South Africa who makes a V shaped dipole which is claimed to work very well and the shape helps with the installation.It has the same name as a certain latex covered object with an internal unbalanced electric motor which I understand is popular with the laydeez :)

 

 

[cscotthendry]

I realise come posts are toung in cheek...FrankM

Frank:

 

Yes, it was a little tongue in cheek (or cheeky) but I chose the title to grab peoples' attention and so that there would be no doubt in their minds what it was about.

 

That said, I've heard transmissions where my radio has unsquelched and there was a bit of a human sounding buzz in the background and I wondered whether the sender had any idea how lousy their signal quality was. Often when I respond to these pilots about their signal quality, I get no reply at all, so I assume from that, that they aren't receiving very well either.

 

I formulated an idea which is essentially the repeater idea put forward by Mark, but had no idea these things already exist.

 

Mick:

 

At the risk of embarrassing myself for not knowing what the correct procedure in that case is (off the top of my head) my choice would be to hover above the circuit height or stand some distance off on the dead side and try to work out where all the RPTs were. Then when they had all landed, I'd join the circuit as normal and land. That is assuming I had enough fuel and light to loiter that long. From my limited observations flying on regional flights as a pax, those guys tend to get into the circuit and get down on the ground as quickly as possible, (and they tend to be fairly large aircraft and easy to spot) so I think the above proposal would be workable.

 

 

[Guernsey]

I'm sure the thread title is tongue in cheek . You simply cannot have less than 1 (unreadable). Just like there is no Year Zero because the calendar started from Year 1.

The next step down is Zero.....your radio is dead.

 

Alan.

 

 

[frank marriott]

Question: You arrive at a busy CTAF® say in a regional city, not long before last light only to discover that other traffic ( RPT's ) in the circuit are not reading your calls at all. You do not have enough light left to go elsewhere ( non radio CTAF ) and there is no coverage to pick up a transponder switched to 7600 to indicate radio failure. What do you do?

Mick

 

Just join the dead side of the circuit and let down to 1000 (AGL) and give way to the right. 7600 is only useful in control not at a regional airport

 

Still transmit your intentions as it may be your receiver and not transmitter working

 

RPT or any class of flight - same rules apply.

 

Do not be intimated by a class of flight. Other then a minority of cases everyone starts somewhere, individuals egos can be deflated

 

when it is required but stick to the rules

 

RPT , Charter etc are all happy if your transmissions are concise and accurate and you will get the relevant response.

 

I have had an occasion to "have a yarn" to a CHTR pilot at an island strip where 4 PVT arrived about correct arrival procedure to find out during the "conversation" that I had done more charter then the individual with the white shirt. - I was not in fancy dress at the time as I did not having paying passengers.

 

Since flying my SFA aircraft I have expected something similar but have found that using correct radio procedure and not carrying on as some of our pilots do I.e. CBradio style then it is not problem.

 

Fly and communicate professionally and you will be accepted accordingly in my experience.

 

FrankM

 

 

[Kyle Communications]

Hi All

 

just to let you know the state of play about the simplex repeater idea. I got hold of the ACMA in Canberra and got the run around for a bit then they hand balled it onto Airsrevices Australia. I got hold of the man in the area and we had at first a "confusion" about what I wanted to do so it was a unequivical NO....I then explained to him again what I wanted but maybe not so much in commercial comms speak and he then understood what I wanted to do. It appears I can do it legally and they are prepared to allocate a frequency and licence for the "base station". I have a few proviso's that will need to be done for the unit like a extra bandpass cavity on the output to limit bandwidth if someone changes the channel...well that isnt going to happen in my locked container but one will go on and a PTT timer to make sure that the unit never remains transmitting which if I cant do in radio programming I can make a simple PTT timer and install it anyway. The simplex board is not in australia so it will be around 10 or 12 days until that arrives from the USA.

 

I have some allocation and licencing fees to pay which is usual as the govt fellas always want their cut that amounts to around $385 for the first year then $40.00 for each year after that so in the scheme of things not bad at all as far as radio allocation and licencing goes it is usually thousands of dollars now especially in what they call "high density" areas

 

I will get all the gear together and made up then apply for the licence after some initial testing so hopefully in around 5 or 6 weeks it will be up on air although I will be testing it from here first for a while to make sure it is all ok and stable so will give out the frequency for the locals to test it on air. When it goes up to Ocean View it should cover for most pilots at least 100 nm probably more

 

If this works well it may start a trend at other places in Australia

 

Mark

 

 

[cscotthendry]

Mark:

 

Thank you so much for your efforts. If you're looking for contributions to defray the costs, count me in for $50.00 for the start up. I'll gladly help with the annuals too.

 

Well done mate!