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Shopping for an Spectrum Analyzer - RF Explorer


miguell2

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For those looking for how to sweep, it has been figured out.

 

https://twitter.com/nerdtalker/status/372557087772925953

 

If you want to know how to sweep, grab a broom.  I will show you.

 

On the other hand, if you want to know how to adjust sweep time, Brian's tweet does not exactly solve the problem.  Sweep/sample time and RBW should be independently adjustable.  But I suspect this is just a limitation of the inexpensive spectrum analyzer.

 

AJ

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If you want to know how to sweep, grab a broom.  I will show you.

 

On the other hand, if you want to know how to adjust sweep time, Brian's tweet does not exactly solve the problem.  Sweep/sample time and RBW should be independently adjustable.  But I suspect this is just a limitation of the inexpensive spectrum analyzer.

 

AJ

Yeah you can adjust RBW from 2, 5, 10, 18, 48, 80kHz, etc... But sweep time not so much.

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If you want to know how to sweep, grab a broom.  I will show you.

 

On the other hand, if you want to know how to adjust sweep time, Brian's tweet does not exactly solve the problem.  Sweep/sample time and RBW should be independently adjustable.  But I suspect this is just a limitation of the inexpensive spectrum analyzer.

 

AJ

You get what you pay for, I suppose.

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If you want to know how to sweep, grab a broom.  I will show you.

 

On the other hand, if you want to know how to adjust sweep time, Brian's tweet does not exactly solve the problem.  Sweep/sample time and RBW should be independently adjustable.  But I suspect this is just a limitation of the inexpensive spectrum analyzer.

 

AJ

 

For those looking for how to sweep, it has been figured out.

 

https://twitter.com/nerdtalker/status/372557087772925953

 

Not sure why he said it wasn't in the manual.  Maybe I'm missing something, but isn't it on page 16?

 

http://micro.arocholl.com/download/RFExplorer_UserManual_v1_11.pdf

 

RF Explorer
User Manual
page
16
Analyzer screen
in Advanced Mode
Alternatively, t
here is a simpler way to increase and decrease frequency span while keeping the center
frequency. As this is a usual workflow, the RF Explorer Spectrum Analyzer screen enables the [Return] key to
switch between standard visualization mode a
nd advanced mode.
In this screen above, the frequency reading at the bottom changed from Start/Center/Stop frequency to
Span/Center/RBW. When this mode is enabled, a key press on
or
button will increase or
decrease to double and half freq
uency span respectively.
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Has anyone checked out the HackRF project? It looks like an amazing candidate for spectrum analysis. It can transmit or receive from 30MHz to 6GHz. With two units you can do full duplex TX/RX and create your own LTE base station, wireless access point, etc... SDR is pretty damn flexible.

 

I have a RTL based TV tuner that can be used for SDR. I know it does at least 30-1700MHz and 2100MHz iirc there are several gaps for what it can and cannot receive.

 

Sent from my IdeaTab A2107A-F using Tapatalk 4

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Has anyone checked out the HackRF project? It looks like an amazing candidate for spectrum analysis. It can transmit or receive from 30MHz to 6GHz. With two units you can do full duplex TX/RX and create your own LTE base station, wireless access point, etc... SDR is pretty damn flexible.

 

I have a RTL based TV tuner that can be used for SDR. I know it does at least 30-1700MHz and 2100MHz iirc there are several gaps for what it can and cannot receive.

 

Sent from my IdeaTab A2107A-F using Tapatalk 4

Wouldn't you need a license to use those? I know Rx you are ok but Tx... I can't image that the FCC or anyone who uses licensed spectrum is going to be too happy about that.

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Wouldn't you need a license to use those? I know Rx you are ok but Tx... I can't image that the FCC or anyone who uses licensed spectrum is going to be too happy about that.

 

It would be up to the person in possession of the HackRF device to make sure they're not transmitting where they shouldn't. They probably even have a disclaimer in their terms and conditions to that effect.

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It would be up to the person in possession of the HackRF device to make sure they're not transmitting where they shouldn't. They probably even have a disclaimer in their terms and conditions to that effect.

I don't know that the FCC would be happy with that if they are selling a built HackRF... they can get around the FCC by selling it as kits... rather than complete products...

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  • 2 months later...

They gotta do what they have to do. It's likely that wimax carriers were still dominating the 2500 range in the Dallas area and they had some in the 2600 range to spare. Clearwire appeared to use different slices of BRS/EBS for each wimax sector which can take up huge chunks  of the BRS/EBS spectrum. 

 

What do you mean by using "different slices"? In my industry, it is common to use different channels for different sectors to maximize the SNR on that sector. Common are ABAb or ABABAB channel setups.

 

I was just about to pull the trigger and buy one, then my router went down.  So I bought a really powerful AC 5GHz wifi router that should cover my entire house and front yard/gazebo.  So I will have to wait on the spectrum analyzer until next month.

 

Robert

 

I think it was already mentioned, but I want to caution you on using Wi-Fi devices with large transmit powers. That large transmit power does nothing for your low power phone or tablet reaching back to the AP. Do it through antenna gain or an increased number of devices with appropriately adjusted transmit powers to not over-step.

 

My Linksys router is a basic model and covers most of my yard, except the back 10 ft and the front 5, and I live on a piece of property approx. 150 ft wide by 300 ft long.

 

 

Sent from Josh's iPhone 5 using Tapatalk 2

 

We have different requirements. My "yard" is 900'x700'. I have 4 APs deployed, but I'm looking to deploy another 4.

 

I'm still rocking a now 8-year-old Linksys WRT54G (v 2.0), which still manages to pump out about 20 Mbps of my 25 Mbps cable connection. It has great range (I lose the signal about half a block down the street), and thankfully I have hardly any interference from the neighbors. That said, the next time my ISP bumps up my speed I'll have to finally retire it, although I'll probably keep it around as a repeater.

 

Linksys went downhill pretty quickly after the WRT54G series, and now that Belkin has bought them I don't hold out any hope that that will change. Everything I've read confirms that Asus is essentially the new Linksys. It's funny that even Netgear is jealous- they claim that if consumers knew that the AC66U's Tx power was too high they'd buy a Netgear instead, but I daresay that would actually make me more inclined to nab it while I can..

 

Given how long I've put off an upgrade already, I'm holding out for the so-called "Wave 2" 802.11ac routers, which will add MU-MIMO, 160 MHz channels, and use 4-8 spatial streams. A tri-band router that adds 802.11ad ("WiGig") on the 60 GHz band is also supposedly in the works. I do wish they'd knock it off with the staggered release schedule and just release routers that implement all the features the AC spec calls for today, but it is what it is. However, for anyone needing a new router this year, I'd definitely put the RT-AC66U (or the newer 67/68U) at the top of the list.

 

Well, look at how long it takes for a new device with the same features on a new chipset takes to develop. Now add all of the new MIMO modes, beamforming, aggregation, etc that haven't been used before. One down-side of AC, though, is that residential customers don't need 80 MHz or 160 MHz. Most don't need more than 10 MHz or 20 MHz. They just make the RF environment worse.

 

Yes and no.  Some of the $20,000 pro spectrum analyzers have the capability to capture and demodulate (but not decrypt) live traffic.  That can certainly be used to assess loading.  As for my basic $1500 analyzer, I can use it to discern when an LTE carrier is live but not active -- only the reference signal bearing subcarriers are present.  But I cannot glean much about loading beyond zero loading.  I am looking only at raw RF, not demodulated LTE, CDMA1X, EV-DO, W-CDMA, or even GSM.

 

AJ

 

Would not the duty cycle of the transmission provide some indicator of usage? Obviously not as good as demodulating it, but certainly a pointer. If there's nothing on the air for X number of milliseconds, there's obviously nothing happening. Conversely, just because it is transmitting doesn't mean you know (unless you have very precise instrumentation) if its running MCS15 or BPSK. I guess - really - knowing what modulation it's using is only applicable to knowing how loaded the data side is, but you should be able to tell (again, maybe you need instrumentation that measures that quickly) how busy the RF side is based upon the presence or absence of a transmission.

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Was messing around with my re-purposed TV tuner stick the other day and found these most interesting.

 

Not sure which provider these are:

 

Low edge

1mIg212h.jpg

 

High edge

64YPIcTh.jpg

 

 

 

Low edge

f246OCAh.jpg

 

High edge

9iDyCl4h.jpg

 

 

 

Something in 800

EDJaN0Gh.jpg

 

Another

9uVDoWUh.jpg

 

 

 

Guessing ATT or VZW in 700.  No idea what I'm looking at in 800.

 

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Guessing ATT or VZW in 700.

 

Both.  AT&T Lower 700 MHz B+C block downlink is 734-746 MHz.  And VZW Upper 700 MHz C block downlink is 746-757 MHz.

 

AJ

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  • 1 month later...

I have used the 2.4ghz version of their product and it does work well but it doesn't solve everything. In one case we still had some clients like phones that were too low power and could "hear" the router but couldn't talk back. We ended up running a piece of CAT5 to the other side of the house and put a cheap everyday router on that side of the house configured as just a wireless access point to solve the issue.

 

We did something simliar at my house, where I am fortunate to have a bit of land....  Ran cat6 under the house, with 3 AP's (it's a long L shaped house), ran fiber to detached garage, and a guesthouse about 300ft away. We put 1 AP in the guesthouse, and 1 in the garage....   have perfect wifi all over the property, but the time and expense on the project was very high. It was fun as an IT guy, but I don't think it's for everyone.

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  • 2 months later...

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