Can you help me interpret this spectrum analysis noise plot?

[Danny D.]

Hi Mark,

Here is a picture of the mount when I had installed it:

The radio itself is the classic Ubiquiti Rocket M2:

That radio is clipped directly onto the back of the dish:

One mistake I made was to use non-shielded cable, so, there's about 75 feet of the plenum stuff outside going from the roof to the first floor office where the router and POE lie.

From a practical (noise) standpoint, how much do you think that matters?

[Tony Hwang]

Hi, B4 you ask that question think about shield? Why do you think we use shielded cable in AF or RF cabling(wiring) CAT 7 spec. ethernet cable is best one. I believe your noise is radio related unlikely Ethernet cable related. Looks like your radio is repeater? All in all if you have reliable connection, what's the worry? One way of increasing signal strength will be using a bigger dish or did you picked best height of the antenna. The higher the better is a myth. Is it LOS install.?

Way back when I was working on microwave, troposcatter links biggest one was troposcatter link shooting from Nha Trang, S, Vietnam over to Thailand. Triple diversity, antenna was 120 ft. square parabolic pair. Nitrogen gas filled wave guides were used. No coax. SWR was around 1.2. One night VC rocket sharpnels made some holes in wave guides plumbing, SWR went upto about 1.4

Tri diversity is based on antenna spacing, frequency, polarization. RX was parametric cavity tuned preamp, and all tube based RX, TX was 10W TWT exciter to 10KW water cooled Klystron driving 100KW bigger Klystron also with water cooled. HV on them were around 27KV DC.

This all became obsolete soon when RCA launched first Commsat. That was end of my career in RF telecomm. going into Digital Data comm, main frames, etc. Worked on autovon/autodin, Arpanet(origin of Internet). Now I am no good any more, things changing too fast to grasp all.

[Danny D'Amico]

I think the shielding shorts out EMI/RFI interference; but, if that interference is, say 60Hz, it won't be the cause of my noise.

My noise is at 2.4GHz.

So, I *think* the shielding isn't really shielding against *my* noise. But it could shield against 60Hz noise (which I'm not measuring).

That's what I think - but I don't really know the answer...

[Danny D'Amico]

Hi Tony,

The radio is not set up as a repeater. It's set up as a router:

As you noted, I do have a reliable connection to the 2.4GHz WiFi access point about 3 miles away, but, since my service is unthrottled, the lower I can get noise, the faster I can get the speeds!

For example, here are side-by-side screenshots of the Rocket M2 speeds versus the Nanobridge M2 speeds the day I switched them out:

Notice, with *nothing* changed other than the dish & radio, on the smaller Nanobridge, I got 78Mbps but on the larger Rocket, I got 117Mbps.

I don't really want to go *bigger* than the Rocketdish, so, that's why I'm asking how to lower the noise.

Note: I see the noise on the Nanobridge was -97dBm, and that of the Rocket is -89dBm, so, it's interesting that the Rocket is noiser than the Nanobridge, considering the beamwidth of the Rocket is far narrower (but the gain is far higher).

[Danny D'Amico]

I should explain that, while I can *fit* a bigger unit on my roof, the RocketDish is already 24dBi and the Rocket M2 radio is already

28dBm, so, the maximum (claimed) gain is 52 dBi (158 Watts), while the maximum legal gain is 36dBm (4 Watts), so, the Rocket is already throttling itself automatically just to keep within legal limits.

So I don't think a bigger dish is really the solution.

The solution is to figure out how to lower the noise...and, the RF Armor seems to be the best answer (albeit pricey).

[Tony Hwang]

Hi, What is operating power of the two radios and what is the sensitivity of two RX? They are built on same design specs? Is it real LOS install or radio horizon install?

[Tony Hwang]

Hi, If you rfeally hae to there iss no such thing as this the problem and this is solution. You need many hours "cut and try type approach". First off like using best cables you can get, even POE injectors are not created equal.

[Danny D'Amico]

Hi Tony,

The access point is a bit more than 3 miles away, line of sight.

NANOBRIDGE M2: Measured signal strength = -68 dBm Measured noise floor = -97 dBm Measured speed = 78 Mbps / 52 Mbps (i.e., 2-channel MIMO) Claimed transmit power = 23 dBm (max) Claimed antenna gain = 18 dBi Calculated EIRP = 41 dBm (12 Watts) Claimed sensitivity = -93 dBm (max) SPEC:

ROCKET M2 + ROCKETDISH 2G-24: Measured signal strength = -64 dBm Measured noise floor = -89 dBm Measured speed = 117 Mbps / 117 Mbps (i.e., 2-channel MIMO) Claimed transmit power = 28 dBm (max) Claimed antenna gain = 24 dBi Calculated EIRP = 52 dBm (158 Watts) Claimed sensitivity = -95dBm (max) SPEC:

[Danny D'Amico]

Hi Tony, With my cabling all less than 100 feet, it really doesn't matter what POE I use with my three radios.

My Bullet came with a half amp 15 volt POE, and my Nanobridge came with an amp 24 volt POE, and my Rocket came with an amp 24 volt POE with its own reset switch (which is really handy since the rocket is on the roof).

In practice, since my cabling is so short, the POE does not matter, as far as I can tell.

Something else *does* matter though ... :)

[The Daring Dufas]

Nonsense, when you quit learning you're dead. You know how to learn which is a quality many people lack. ^_^

TDD

[makolber]

A bigger dish will help. I was asking about the RF cable, not the Ethernet cable. I think what you want to do is read up on the subject. Here are some key words to search for info Noise figure G/t Link budget Path loss Thermal noise

-174 dBm / Hz Noise bandwidth Spectrum analyzer noise measurements Parabolic reflector Beam width Aperture size Also it seems your real goal is to increase the data rate but you seem focused on the ex noise. Don't forget,the link needs to go both ways. Step one is to determine which path direction is your limiting factor. Have fun... Happy new year Mark

[Danny D'Amico]

The RF cable is as short as it can be, since the radio is clipped directly into its mount on the back of the dish.

RF line losses are as low as I can make them without additional shielding.