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Re: Filters
¿ªÔÆÌåÓýMorris Engelson¡¯s book on spec ans from the Tektronix Measurenents series is good, and downloadable from the TekWiki site. Also, Dan Welch¡¯s book from the Tektronix Concepts series is good and also downloadable from TekWiki. DaveD On Oct 12, 2021, at 17:48, James Belcher <theburp@...> wrote:
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Re: Filters
James Belcher
¿ªÔÆÌåÓýThanks Evan and Clyde, ? I would like to read up on SAs but can find no decent book on them on Amazon.? If you have a reference I would be interested. ? That being said, I do not really plan to do much in the RF range, mostly in the audio range for study. ? I actually have a very strong back ground in electronics.? Its just that I have never spent any real time in this kind of electronics, and wish to improve my knowledge. ? The idea was to build a simple filter (bandpass, band reject etc) as low to moderate frequency mainly to learn to use the equipment. ? Jim ? From: [email protected] <[email protected]>
On Behalf Of Evan Hand
Sent: Tuesday, October 12, 2021 9:26 PM To: [email protected] Subject: Re: [tinysa] Filters ? Hi James, |
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Re: Filters
Hi James,
There are two different "nano" based devices that are cheap and available for RF and RF circuits measurement.? Each has its own strengths and weaknesses.? To simplify (ALWAYS dangerous, so please take with a grain of salt); the NanoVNA is good at measuring circuits that do not supply their own RF and the TinySA is used to measure outputs of circuits that do generate their own RF. For what you are stating that you want to do, the NanoVNA is the best tool.? You can use the TinySA to do the measurements per the video from Erik.? It takes more fiddling and may be less accurate.? It also takes an external noise source to generate the RF for the TinySA to measure.? The RF generator is built into the NanoVNA and is calibrated across the frequency range of measurement within the capabilities of the device.. By the same token, you can use the NanoVNA to do spectrum measurements with less accuracy and more fiddling. I would have less confidence in the measurements that the device was not designed to do.? With that said, if you understand the details of the limits of the measurement device, you can use it. I would suggest that you read up on spectrum analyzers and vector network analyzers to get an understanding of how they work.? This is more so as you are studying electronics, and a deeper understanding of how the measurements are made will help. Above are just suggestions.? Have fun learning about RF circuits and measurements. 73 Evan AC9TU |
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Re: Filters
¿ªÔÆÌåÓýI don¡¯t know. ?I haven¡¯t a clue on how to do what I want to do. ? From: [email protected] <[email protected]>
On Behalf Of ?????? ???????
Sent: Tuesday, October 12, 2021 7:12 PM To: [email protected] Subject: Re: [tinysa] Filters ? On Mon, Oct 11, 2021 at 01:59 PM, <theburp@...> wrote:
Why just not to get a proper tool like nanoVNA? |
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Re: Cal Out anomaly
¿ªÔÆÌåÓýThanks, Erik. It was just an observation, and now I have an explanation.On 10/10/2021 10:08 PM, Erik Kaashoek
wrote:
When you enable cal output you get TWO signals from the high output. |
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Re: Cal Out anomaly
When you enable cal output you get TWO signals from the high output.
1: The low frequency cal output (with harmonics) 2: The leakage from the LOW INPUT mode LO Once you enable HIGH INPUT the LO is switched off and the "noise" and the interference (leading to small level fluctuations) disappears This is normal behavior and has no impact on the power level calibration using the cal output -- ------------------------------------------
For more info on the tinySA go to https://tinysa.org/wiki/ |
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Re: Cal Out anomaly
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On Oct 10, 2021, at 1:00 AM, Erik Kaashoek <erik@...> wrote:
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Re: Cal Out anomaly
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On Oct 10, 2021, at 1:00 AM, Erik Kaashoek <erik@...> wrote:
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Re: Questions Re Measuring IIP3 Of LNA
The 6dB attenuators are to ensure the signal generators do not create harmonic products caused by the signal from the other generator. Isolation.
The input signal to the LNA should be such that intermodulation products are strong enough to observe, so well above whatever the tinySA may generate internally. Being close to the compression point of the LNA for sure will generate a lot of intermodulation. -- ------------------------------------------
For more info on the tinySA go to https://tinysa.org/wiki/ |
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Re: Questions Re Measuring IIP3 Of LNA
It looks like you have 6dB attenuators before the SMA tee.? Why is this given that (presumably) you can just adjust the level of the signal generators? Bryan |
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Ali express now selling TinySA without the TinySA logo
Still the same description, but they call it an improved version. However, reading through the fine print they say that the self test might fail especially after software upgrade. They do maintain that the function is not impaired, a statement we all know is bogus.
The link is for entertainment purposes only, not a buying recommendation, unless you want to waste your money since you will NOT get a money return from Ali Express for those units. After all they warn you about all the short comings. John |
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Re: Uhf TV monitoring, Antenna testing
Hay OneofEleven, I was re-reading your earlier reply and noted you apparently were referencing transmitters, so I assume you are talking about broadcasters. I was describing closed cable TV systems. Here our off air broadcasters also publicly publish their carrier data just like? the satellite operators do. But even for them, where they reside on a cable systems spectrum, on which EIA carrier they are embedded on, that data is not general knowledge outside the system. Great thing about digital programming is that you can put a program anywhere in the spectrum and call it up under whatever channel number you choose to assign to the set top box. With this technology, you can get real deep in the weeds. But the core interest here is how convenient, accurate, and economical the TinySA as a spectrum analyzer is to be able to effectively make reliable measurements of these carriers. Cable systems spend 3-5k $ to equip field techs with instruments to measure levels and digital parameters, most have a rudimentary spectrum analyzer function which is useful but not flexible for in depth analysis.? ?
----------------------------------------- From: "OneOfEleven"To: [email protected] Cc: Sent: Thursday October 7 2021 2:34:41PM Subject: Re: [tinysa] Uhf TV monitoring, Antenna testing On Thu, Oct 7, 2021 at 09:14 PM, Ted Chesley wrote: Normally the only programming data available to the customer (or outside observer) is the listing of program channels as tuned by the digital set top box. Tables of programming maps to the individual carriers, as well as dedicated band assignments are only available to the systems technical personnel.??I guess we're lucky in the UK then by the sounds of it because we're given all the transmitter site details (transmitter location, expected coverage, list of TV channels on which multiplexed streamed, stream center frequency, bandwidth, power and modulation). ie .. |
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Re: Uhf TV monitoring, Antenna testing
Hi One of Eleven, Yep I would say you are better informed than most customers (or outside observers) in the US. Normally, here, that info is not widely disseminated outside the systems. With clear channel QAM and a network analyzer you can find most of the embedded carrier characteristics, but as almost all data program transmissions are encrypted (even the off air broadcasters),on the cable, it's more difficult. Some smaller rural systems or stand alone operators still carry un-encrypted digital but the big guys do not. In contrast, as? you know, in the satellite world, there are charts of this info widely published as it is necessary for the individual customer to program his own receiver, but in cable this is done from the network, or central headend, and the customer has no control over the process. Also, considerable manipulation of programming occurs frequently and these programming matrix's are constantly changing.
I have done a lot of work in the EU, back in the early 2000's, on cable, but that was primarily PAL Analog carriers.with a few DVB-C carriers thrown in. I understand a lot has changed in the last decade. ----------------------------------------- From: "OneOfEleven"To: [email protected] Cc: Sent: Thursday October 7 2021 2:34:41PM Subject: Re: [tinysa] Uhf TV monitoring, Antenna testing On Thu, Oct 7, 2021 at 09:14 PM, Ted Chesley wrote: Normally the only programming data available to the customer (or outside observer) is the listing of program channels as tuned by the digital set top box. Tables of programming maps to the individual carriers, as well as dedicated band assignments are only available to the systems technical personnel.??I guess we're lucky in the UK then by the sounds of it because we're given all the transmitter site details (transmitter location, expected coverage, list of TV channels on which multiplexed streamed, stream center frequency, bandwidth, power and modulation). ie .. |
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Re: Uhf TV monitoring, Antenna testing
On Thu, Oct 7, 2021 at 09:14 PM, Ted Chesley wrote:
Normally the only programming data available to the customer (or outside observer) is the listing of program channels as tuned by the digital set top box. Tables of programming maps to the individual carriers, as well as dedicated band assignments are only available to the systems technical personnel.??I guess we're lucky in the UK then by the sounds of it because we're given all the transmitter site details (transmitter location, expected coverage, list of TV channels on which multiplexed streamed, stream center frequency, bandwidth, power and modulation). ie .. |
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Re: Uhf TV monitoring, Antenna testing
Jose and Dave, I have attached a doc with a quick overview of the layout of the typical cable TV spectrum (USA). Might be helpful to those interested. I have also attached a doc on measuring the 256 QAM carriers in such a system with the TinySA.?
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The cable spectrum is fairly consistent in general layout, the complexity exists in the allocation of EIA's (channels) into dedicated service bands, and the embedding of programming in each of the carriers. However, as this is done through centralized digital network programming it is not apparent to someone observing the spectrum on an analyzer.? Normally the only programming data available to the customer (or outside observer) is the listing of program channels as tuned by the digital set top box. Tables of programming maps to the individual carriers, as well as dedicated band assignments are only available to the systems technical personnel.?? There are a myriad of issues that affect cable transmission, ingress of interference, response over such a wide bandwidth, transmission delays, reflections, variation with temperature etc. it's a wonder the systems work as well as they do given hundreds of miles of plant and thousands of connections in a typical system. ?? ----------------------------------------- From: "DAVE REISER"To: "[email protected]" Cc: Sent: Monday October 4 2021 7:02:12PM Subject: Re: [tinysa] Uhf TV monitoring, Antenna testing I would be interested in seeing one.? Here is the raw data to make one.? In the QAM column, each channel can have 10 or more 6 MHz channels compressed into one QAM 6 MHz channel.? Also channel numbers don¡¯t follow.? ??For example, if I want to watch channel 975 my set-top converter will tune to channel 121.? That¡¯s totally up to the cable company. ? Kind Regards, Dave Dave Reiser Phone: 301-216-5394 Mobile: 301-802-1929 Email:? davereiser2outlook.com 520 Russell Avenue, Gaithersburg, MD 20877 ? From: [email protected]
<[email protected]> On Behalf Of Jose Cruz
Sent: Monday, October 4, 2021 3:10 PM To: [email protected] Subject: Re: [tinysa] Uhf TV monitoring, Antenna testing ? Is there some type of overlay to see the Tv
channels portion of the spectrum? |
John Cunliffe W7ZQ