Using remote receiving to chase / noise problems

On the Bands
1

After this weekends attempt to chase Andy, MM0FMF/P on GM/SS-135 on 60m, I’ve felt motivated to post my frustrations on my receive capability from a ‘average’ to ‘good’ domestic location.

With this problem there seems to be no obvious solution other than to move away from everyone in existence to get a noise floor which is both stable and low.

What is really really hacking me off is the continually rising noise floor of many low frequency HF operators around the UK. I notice this as an Activator observing others and my own experience. So some background information of my own situation.

I moved to Cambridgeshire in 2016, found a small bungalow on the outskirts of a Fenland town known as Chatteris. It has open fields from about 5 houses away, a large field to my immediate left and some fairly well spaced houses across the street. No solar panels in the immediate surrounding area. Seems OK, an initial sweep with the KX3 when I arrived there for the viewing seemed all good. Great I thought, once some larger wire aerials were put up, not so great…

Aerial’s at the moment…
1/4 L 38 meters long, tuned at the base with an Icom AH3. Large countapoise array, no ground spikes currently.
1/2 L inverted V dipole for 80M 50R ~ 3.56MHz
Both coaxially fed, choked with GM3SEK HmBrew baluns and kept well away from any mains wiring.

I’ve tried different feeding techniques, balun positions you name it still gets in !

20170507_152220.jpg3301×2476 2.25 MB

Inverted V(80m) (back) (L towards the front)

Google maps

blob.jpg1311×920 655 KB

Noise levels can be as high as S7-9 depending on time. I can hold a QSO easily on 60m in the evening. The variation is large enough to stop a casual chase on Sunday afternoon.

My thoughts are next to investigate and plot the noise to hopefully find its source. I would be interested to know of similar experiences from others and what / if they managed to resolve their problems / what technquies they used and how they feel currently.

If I cannot improve the situation, remotely receiving is going to be the only option. To quote Les Moxon in one of his books “Using two separate antennas to receive and transmit is not a good idea” apart from that it feels like cheating !

Bizarrely though 160m is rather good !! 5 MHz and 7 MHz bands are poor noise wise and the bottom end of 3.5 MHz band

Or I could just move again…:persevere:.

Jonathan :worried:

2

Noise receiving antenna and a phasing unit. Pickup noise on the “noise antenna” and mix it out of phase with the main antenna. You can then reduce the noise at the radio. If you radio doesn’t have separate RX/TX sockets you’ll need a C/O relay to switch the phasing unit out of circuit. Google is your friend.

3

But that only works if the noise has corrolation with the noise in your demodulated passband. . no ?

Herd of that technique, wasn’t confident enough to try it

4

Jonathan, I have both Dipoles and OCF antennas up at my QTH and have found the OCF with it’s much better SIGNAL/Noise performance is almost always better than my Alpha-Delta fan Dipole by roughly 10-20dB (on the P3, Panadapter). Both of these antennas are up at around 50-65ft…

The OCF I use (home QTH) has the dimensions suggested in the K1POO write-up… 57ft / 12ft but it’s a 10-40m performer… I did use a double dimension version for Winter field day and that worked well also.

Richard // N2GBR

5

It will reduce the noise at the RX input by “some” dB where “some” depends on the local situation. Hey it may only knock a few dB off but that would still be worth investigating.

6

My situation is similar, with the noise S7 on 20 metres and 8-9 on 40 to 80, but Top Band tolerable.

This only works on one noise source at a time. I don’t know if you can cascade them for the multiple sources that exist around here.

I find the OCF dipole a little better than a doublet.

As for remote receiving, I think I would rather go QRT!

7

Oh yes you’re right. Well I’d go QRT then Brian.

8

Hi Jonathan,
I bought my curent QTH in a very small village 18Km SouthWest of Pamplona mainly to get rid of flat building neighbours and the associated complains, sabotage and other problems I had to deal with in my early years on this hobby, along with the QRM coming mainly from a nearby big bank building when my beam was pointing to NorthAmerica.
That was back in the 80’s and today’s scenario has little to do with what it was then, while I was living in a flat in the centre of Pamplona city. Nowadays, we have several electronic devices like plasmas, battery chargers, LED lamps, etc.
Even in the small village where I live now, which is in the middle of the country with extremely low levels of QRM most of the times, such idilic scenario can get ruined and it actually does by just one single nearby neighbour having a LED lamp.
This is what I’m currently experiencing and not only one neighbour but three of them around my QTH have been identified as owning and using some noisy LED lamps in 2 cases and something else I haven’t identified yet in another case.
This non identified electric device is the worst, as it makes my S-meter go up to a constant S9+20dB. When that device (whatever it is) is ON, I just switch my radio OFF and go away.
One of the other 2 neighbours is an ex-work colleague and I still have a good relationship with him, so I send him a begging whatsapp message if I see he has his big garden LED lamps ON when I want to listen for some weak Northamerican activator. Fortunately he’s kind so far and he usually switches off his LED lamps as soon as he gets my message.
But LED lamps are here to stay and spread all over, I’m afraid, so this is going to be a real nighmare for us.
Due to family needs, I’ll be renting a flat in Pamplona city next week and we will move there with big shame in my soul for leaving behind my beloved low noise QTH, my tower, my yagi…
I don’t know yet how the QRM levels will be like there in the new rented QTH but I’m mainly pesimistic.
My days of chasing Northamerican activators in the evening will soon come to an end or at least to a break.
Maybe I’ll have to start thinking about remote operation from the flat in Pamplona to my QTH in the country with its yagi and its low noise levels, as long as the LED lamps remain OFF.
Cheers,

Guru

9

Having just got back into the hobby after a 20 year break I had assumed living in the middle of the Pennines would be completely noise free. On closer inspection there are some issues. The house is surrounded by wires, overhead mains and telephone cunningly positioned to intersect with any wire antenna in any direction. One of the neighbours has solar panels which seem to add noise but the biggest problem is ADSL / VDSL. Unfortunatly this seems to cause problems both ways with my transmission knocking out the ADSL on 160m and noises on all bands up to 50MHz varying between s3 and s8. There is also something else ( still to identify ) which is not on ofen but gives me S8 noise on 160 - 40 and s5 up to 15m. There is some light at the end of the tunnel. As superfast broadband does not make it down the 2km of copper wire to the exchange ( 8Mb is the most stable speed I can get with filters installed ) the improvement planned is Fibre to the Premises due later this year… perhaps the noise will go if I can persuade the neighbours to take it?

Good Luck!

10

Thanks for the replies, especially yours Paul.

I have homebrewed a copy of M1GEO’s clone of the Wellbrook loop a few months back. Last night I went for a walk with the KX3 using the loop to look for strong sources. I have already done this, but its a bit tedious holding the bias tee loop and KX3 on ones person whilst walking about.

I set it up on the 3.5 MHz band which is typically where the loop performs best. I have noticed the variations on my own VDSL line which snakes around the house which can radiate a strong broadband noise across the lower HF bands. This depends on activity levels, strongest mid weekend typically.

Immediately across the street is the FTTC on the other side of the street facing New Road is the main ‘feed’ pole with 15 or so lines from it. Directly under that pole the noise was 56-60dB over my receiver noise floor !

Nulling using a loop is an option. I feel compelled to contact OpenReach and complain at this stage. I want to gather more evidence first. I find it amusing as I walk to more houses closer together the noise actually decreases :smile:

A similar situation, although this focuses on 10MHz in particular

I will report progress on this, in the 6-7 months of moving into the property I have not had chance to study and resolve this properly. I hope if I do find a solution, it is of help to others trying to chase weak signals on the lower HF bands.

Jonathan

2 Likes
12

Something came up in QSO other day.
I know with Sota there is no relaying of via internet including SDR for TX
Does this also apply to the chaser whom may be using SDR via internet as RX unit.
But how does this effect if one is just a IWSL using same method of chasing Sotas via inter SDR for those no have ham licences and the short wave listener as we do have a section of chasing via ISWL scoring.

Answers on a post card please

karl

13

Que?

14

Hi Karl,
I think you are asking two questions:

  1. Is it valid to SOTA chase using a remote SDR to RX on and your own local TX?

  2. Is it valid to SOTA chase as a SWL using a remote SDR to RX on?

Am I correct?

73 Andrew G4AFI

15

And he has just started a new discussion on an entirely new thread based on what I have already started…

Que indeed.

16

ISWL = International Short Wave League

SWL = Short Wave Listener / Listening

You’re not the first, nor I suspect the last to get the two concepts confused. They are completely different things though. I believe you’re talking about SWL, not ISWL.

And yes, we (MT) should move all this thread and merge it into the existing thread started by Jonathan. Which I hope I have just done … :slight_smile:

18

You can use an internet based RX as long as it is always the same RX in the same location. Or you can use your RX at your QTH. Either but not both.

19

ANDY thank u for that.

karl

20

Can you clarify whether this statement is ex cathedra from the MT or a personal view?

It seems to raise more questions than it answers. Are you saying that if you ever use a remote receiver for chasing you can never use anything else? That doesn’t seem consistent with the general principle that all chases count whereever you are.

The General Rules seem silent on the matter so I cannot see any general principle that you might be applying here.

Martyn

21

I understand Andy’s statement from a point of view from logging whilst receiving from two different locations would skew a potential advantage over a typical home station. Further clarification maybe needed on this as the availability and necessity of remote stations become popular. With VDSL existing everywhere nowadays, this is the only alternative for many.

Going QRT is the sign of a quitter Brian, that resembles the attitude of idiots that get into this hobby like they would golf or fishing by buying everything off the shelf “Ugh it doesn’t work”.
I will strive for a technical solution to this, just like my predecessors did when they faced problems of a different nature.

23

I believe we discussed it at the MT meet. The rules have to catch up still. My personal view is I don’t mind but others were most against using many remote RXs as that gave people chasing advantages. Hence the idea of you useing your own RX or a remote one irrespective of where you and your RX maybe. It’s difficult to police of course.