New Endian FreqFinder

[Jack Norflus]

Please forgive my ignorance, but why would an intermod. app. not be necessary for digital radios? They still use RF, right? To which radios are you referring? Do yours have some sort of intermod. avoidance functionality built in? What am I missing?

Billy uses exclusively Zaxcom wireless and IFB's. Zaxcom digital wireless does not cause any intermodulation.

[Derek H]

I agree, it would be nice to be able to switch off the intermod calculator if you are just interested in locating the significant TV towers the area.

[studiomprd]

" if you are just interested in locating the significant TV towers the area "

That is easily accomplished with a scan...

[NewEndian]

While I do not mean to downplay Zaxcom transmitters in any way, a radio signal being digital does not preclude it from causing intermodulation. I'll have to explain more a little later. But to answer some other questions:

Android and iPhone are definitely the two platforms to be released in the near future. Release will happen in the next few weeks on the Apple store and Android markets.

TV data will be downloaded directly from the FCC database, which is as up to date as I can be.

Zaxcom will be supported in a future update and will have some intermod calculation for it. The intermod functionality though is not so strict at the moment as to severely limit the number channels put on any one block. That said, channels will of course be able to be selected outside of the suggested channels, and my plan is to build more configurability into the intermod, so turning it off will be an option.

FreqFinder should be used in conjunction with a spectrum analyzer. But having the TV data actually does help beyond the noise floor of a spectrum analyzer (at least the ones I have access to) in my experience.

[bigmaho]

Hi Tom,

Analog (FM) radios use numerous internal frequencies that they add and / or subtract to create the carrier frequency. Digital radios (Zaxcom and Sony) do not mix intermediate frequencies, so they do not suffer from intermod interference. Digital radios can be placed 500-600 khz apart with no other considerations (as long as the frequency is clear of other transmissions). With my FM radios there is a complex algorithm to determine what freqs work together. No such algorithm is necessary with my Zaxcoms. Sony digital radios use a similar process as the Zaxcoms. I'm not sure if this goes for all other digital radios (though I assume so. Take digital cell phones for example, they do not have to take intermod into account when numerous phones share the same venue).

Best,

Billy Sarokin

Billy,

Please forgive my ignorance, but why would an intermod. app. not be necessary for digital radios? They still use RF, right? To which radios are you referring? Do yours have some sort of intermod. avoidance functionality built in? What am I missing?

~tom

[bigmaho]

Not exclusively Zaxcom, I still keep 2 Audio Ltd's on my car and mini rig when using the 'stick' mic (Audio Ltd HX and HXIR).

Billy uses exclusively Zaxcom wireless and IFB's. Zaxcom digital wireless does not cause any intermodulation.

[bigmaho]

Yes, but an app would be helpful in prep to know what is currently in a given area. I find any charts I find on line to be very inaccurate. Which I guess means this app might also be inaccurate unless he's found a better source of current data!

Billy

" if you are just interested in locating the significant TV towers the area "

That is easily accomplished with a scan...

[bigmaho]

Digital transmitters use an entirely different type of modulation than analog radios. I'm not an rf expert, but most FM radios employ an intermediate frequency that is combined with another frequency to create a carrier on a third freq so it generates rf at the carrier and the carrier plus the IF and the carrier minus the IF, so each radio transmits on 3 frequencies, so when selecting additional frequencies for a group of radios all 3 frequencies must be taken into account to. On the other hand, digital radios do not use an intermediate frequency so only the carrier and deviation must be taken into account. The digital signal is approx 500 kHz wide. Other than that, transmitters can be set end to end, for instance 680.0, 680.5, 681, 681.5, 682, etc. I find it much easier to change frequencies on my digital radios. I can re-freq all 12 of my radios in seconds if need be without using any software. So while I would have no need of your app (though it would be invaluable for the majority of users who use fm transmitters) I would love the other feature of the app if it keeps itself current.

Best (and good luck!!)

Billy

While I do not mean to downplay Zaxcom transmitters in any way, a radio signal being digital does not preclude it from causing intermodulation. I'll have to explain more a little later. But to answer some other questions:

Android and iPhone are definitely the two platforms to be released in the near future. Release will happen in the next few weeks on the Apple store and Android markets.

TV data will be downloaded directly from the FCC database, which is as up to date as I can be.

Zaxcom will be supported in a future update and will have some intermod calculation for it. The intermod functionality though is not so strict at the moment as to severely limit the number channels put on any one block. That said, channels will of course be able to be selected outside of the suggested channels, and my plan is to build more configurability into the intermod, so turning it off will be an option.

FreqFinder should be used in conjunction with a spectrum analyzer. But having the TV data actually does help beyond the noise floor of a spectrum analyzer (at least the ones I have access to) in my experience.

[John Blankenship]

Yes, great idea! Another potential user for the Android version here.

[Bash]

Regarding digitel wireless and intermof free, and I am no expert on this, but....

I think the percieved wisdom is that you can run a number of digital radio mics together, and not worry too much about intermod as whatever is going on with the digits, you are highly unlikely to 'hear' any intermod artifacts. The audio is carried in a stream of ones and naughts within the radio signal, and although there may be intermod stuff goingon in RF land, this will not be carried through to the actual audio. So, in practice, the error correction, interpolation, and other digital failsafes, that ensure that the digits arrive in more or less the right order, will also make the audio sound 'right'.

On the other hand, when the audio is transmitted as an analogue signal, within some form of RF carrier, and another is working nearby at a frequency that might cause some form of harmonic, then an audio artifact will inevitably be heard.

Simples innit!!

sb

[NewEndian]

Billy, the intermodulation you're referring to occurs within one transmitter. The intermodulation I'm referring to occurs between transmitters and occurs with digital radios including WiFi, OFDM, CDMA, etc. In fact, it is one of the contributing problems with the Lightsquared LTE incompatibilities with the GPS spectrum (http://www.insidegnss.com/node/2663)

Intermodulation occurs when any two frequencies are passed through any non-linear circuitry. This could be at the input stage of a receiver before it hits the bandpass filter, or it could be in the transmitter at the radio power amplifier (negative feedback causes external radio to be passed through the amplifier). While no circuitry is perfectly linear, the major cause of non-linearity for our purposes is when the receiver input or the radio power amplifier gets overdriven into its non-linear range.

I of course can not talk about Zaxcom's electronics specifically, but my guess would be that the reason for Zaxcom's squeezability is it's relatively low power output. I've fit 30+ channels of sennheiser analog transmitters at 25mW and been fine, except when I laid them all on top of each other, but it's relatively infrequent that 30 reality talent all jump on top of each other.

That said, you guys are making me realize that I should make the app a little more friendly to those who only want to use the TV station finding portion. In that case I'll at least give the option to disable the intermod warning icons on the front screen. And I'll spend more time making the TV add-on a little more feature rich.

Billy, I've got you covered.

Cheers,

James

[bigmaho]

Billy, the intermodulation you're referring to occurs within one transmitter. The intermodulation I'm referring to occurs between transmitters and occurs with digital radios including WiFi, OFDM, CDMA, etc. In fact, it is one of the contributing problems with the Lightsquared LTE incompatibilities with the GPS spectrum (http://www.insidegnss.com/node/2663)

Intermodulation occurs when any two frequencies are passed through any non-linear circuitry. This could be at the input stage of a receiver before it hits the bandpass filter, or it could be in the transmitter at the radio power amplifier (negative feedback causes external radio to be passed through the amplifier). While no circuitry is perfectly linear, the major cause of non-linearity for our purposes is when the receiver input or the radio power amplifier gets overdriven into its non-linear range.

I of course can not talk about Zaxcom's electronics specifically, but my guess would be that the reason for Zaxcom's squeezability is it's relatively low power output. I've fit 30+ channels of sennheiser analog transmitters at 25mW and been fine, except when I laid them all on top of each other, but it's relatively infrequent that 30 reality talent all jump on top of each other.

That said, you guys are making me realize that I should make the app a little more friendly to those who only want to use the TV station finding portion. In that case I'll at least give the option to disable the intermod warning icons on the front screen. And I'll spend more time making the TV add-on a little more feature rich.

Billy, I've got you covered.

Cheers,

James

Thanks!!!

[NewEndian]

For people interested in the FCC database, here's the link:

http://transition.fcc.gov/fcc-bin/audio/tvq.html

[Phil D]

+1 more for android

frequency finder sounds perfect

[studiomprd]

" there may be intermod stuff going on in RF land, this will not be carried through to the actual audio. "

+

" relatively low power output. "

+

physical separation

I think you're on to something...

[NewEndian]

So here's my plan: I am going to submit the iPhone version to the app store this weekend. There is more work to be done on the android version so I'm hoping to have it ready by the time the iPhone version passes review.

Listening to your comments, I have decided to expand the TV portion of the app (to make sure people who don't care about the intermod calculator feel like they're getting their money's worth). So for this release, the TV functionality will be enabled as a preview while I continue to develop it. I will set it to expire at the end of January, at which time it will require the $15 fee for the added functionality.

What to expect for now:

The preview TV functionality will only apply to your current location (I had to tear down the old TV UI for the redesign). It will give you an estimate for the strength of any tv signals at your current location for the selected transmitter. And during channel selection each option will display the effecting TV channel's estimated signal strength for your location. The algorithm for the field strength estimate is derived directly from the FCC F(90,50) propagation curves.

http://www.fcc.gov/encyclopedia/fm-and-tv-propagation-curves-graphs-sections-73333-73525-and-73699

The programmer for the audio devision at the FCC was kind enough to give me the source code to the program used to generate these graphs. It was in FORTRAN (all caps is the official spelling, I believe), though, so it took a little bit of work to port it to iPhone and Android friendly code. There's an online version here:

http://transition.fcc.gov/mb/audio/bickel/curves.html#START

*NB The FCC curves are a clever combination of testing and theory. They are used to determine acceptable distances between towers on the same channel to protect the target area from interference. They are still estimates. Also, the app's calculations currently do not take antenna directionality into account, but I intend on figuring that into the algorithm by the official release date for the add-on.

What is coming to the TV add-on:

- The ability to store sets of station data for specific locations, for the purposes of planning ahead and for offline mode

- Google maps integration with markers for stations as well as the FCC antenna contours for the stations

- Station antenna directionality built in to the field strength estimates

All of this I will be adding into the app during the preview phase so you kind folks can test and play around with it.

If there are any objections to this method of release, please share. Apple very well may not go for it actually. They do not like beta-like things. However, the full functionality of the intermodulation calculation is included in the app now. So for anyone who does not live in the US, the app is complete for your purposes.

Cheers,

James

[taylormadeaudio]

+11

~tt

[NewEndian]

FreqFinder for iOS version 1.0 is officially submitted for review! Time to finish up the Android version.

[NewEndian]

FreqFinder for iOS now available!

http://itunes.apple....40427?ls=1&mt=8

Remember that the full TV Add-on is not available yet. However, preview TV functionality is included until February.

LectroRM users (everyone, right?): while the interapp communication is currently built into FreqFinder, I'm still waiting for LectroRM 1.43 to pass through the app review, at which point the FreqFinder will be able to share the LectroRM functionality.

I gave manglermixer.com a copy in hopes that he would do another video. Feel free to wait for that so that you can see exactly what you're getting (no pressure, Michael).

Android users, I'm still chugging away. Hoping to get it up on the market by the end of the weekend.

Lastly, let me just say what this is not: this is not a silver bullet. This is a way to calculate and consolidate on the fly information that is important when making transmitter channel selections. I put a lot of hard work into the research and programming, and I will put in much more until I feel that there is nothing more that should be added or changed. I know you guys will help me to do that. Thank you all for your support.

Cheers,

James

[WhyOne]

James,

Just bought it and playing around. Pretty intuitive on the compatibility side, but when I hit OK on the TV Preview disclaimer window, FF crashes... Any thoughts? This is on an iPhone 4.

Jay

[NewEndian]

Deepest apologies everyone. I've been doing most of my testing with iOS 5. iOS 5ers won't have a problem. I know where the problem is for iOS4, and will post the fix immediately.

[Matt Bacon AMPS]

Hi James

I've emailed you direct with my first impressions and thoughts on UI and functionality.

Regards

Matt

[chris_bollard]

I understand your concern about horsepower and portable devices so your 12-16 recommendation.

Is this a programme limit ? Or can I chug along in slow lane to Coord larger number of Tx? My current project is beyond this limit and as we move every week a portable solution would be great.

[NewEndian]

Yes, it is horsepower. There are no preprogrammed limits. The fewer blocks you use, the faster it will be. Also, I actually will be programming some speed improvements soon. Such as taking better advantage of the iPhone 4S's dual core chip and having results appear during the calculations.

But I really can't recommend slow lane. If you can wait, I've learned a few new tricks while working on the Android version (my Evo actually can handle 20+). I'll incorporate them into the iPhone version after the Android version is released

-James.

[taylormadeaudio]

Just bought the app -- inputting freqs for use on location in NW Washington this weekend... will report early next week.

~tt