I have been doing some research on filters ( I know have a headache) and saw in the easier to read manual for the SDS 100 that they add countermeasures especially in VHF and UHF. Is the 800 band considered UHF?
SDS100/SDS200: Are Filters just for UHF VHF?
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nd5y
Member
VHF is 30-300 MHz and UHF is 300-3000 MHz.
The manual author and filter manufacturers may have different definitions for what they consider UHF.
The manual author and filter manufacturers may have different definitions for what they consider UHF.
Wireless technology started at the low end of what we now refer to as the radio spectrum. Advancements allowed opening up the higher frequencies and these new frequencies were tagged “Very High Frequencies” (VHF). 30-50MHz was referred to as VHF low Band when the VHF High Band came to be. Later, additional progress in the technology allowed for the use of even higher frequencies and they got tagged Ultra High Frequencies (UHF). When the 700/800MHz band came into existence some, probably out of conformity, referred to it as the Ultra Ultra Frequency Band (UUHF). However, I haven’t heard anyone refer to it as UUHF in quite some time… it’s usually called the 700/800MHz Band. There may still be slight confusion as to what category does a particular frequency belong to… I've heard people ask “Just to be clear, when you refer to the UHF Band, what frequencies apply?”
According to some of the RR posts, Uniden did not provide any parameters or instructions regarding these settings.
iMONITOR
Silent Key
What are you trying to accomplish? Countermeasures for what? Your post is a little vague.
Ubbe
Member
It's a headache as there's no rule to follow how to use the different filter settings. You have to try them all until it seems to improve an interfered reception. It's just as much problem in all frequency bands but the lower in frequency you go the more it seems to have an impact on the squelch operation. If you take the antenna off and set a search range of 10-20MHz and look at the display, it will search pretty much uninterfered in the 800Mhz band. In the 400Mhz band it sometimes gets a reaction from the squelch and the search stops briefly. In VHF it stops at lot.
SDS100.mp4
drive.google.com
/Ubbe
Trying to figure out how filters work and why. Countermeasures was the words used in the easier to read manual.
ka3jjz
Wiki Admin Emeritus
I think the word 'countermeasures' was a bad choice - perhaps 'adjustment' would have been better.
And as to how the filters work, there have been NUMEROUS discussions on this very topic. As mentioned elsewhere, they are very hard to quantify as to say 'this setting is the one you should use'. One setting might work for one user, a completely different setting for someone else. Uniden has been very quiet on this topic, so anything that has been discovered has been by the hard work and experimentation of various folks. I think I read somewhere - and I could be wrong here - was that Uniden really didn't want folks to figure this out, hence the silence.
A file on how the filters seem to operate, and a link to the many discussions on this topic, can be found in our SDS FAQ, viz.
wiki.radioreference.com
Mike
And as to how the filters work, there have been NUMEROUS discussions on this very topic. As mentioned elsewhere, they are very hard to quantify as to say 'this setting is the one you should use'. One setting might work for one user, a completely different setting for someone else. Uniden has been very quiet on this topic, so anything that has been discovered has been by the hard work and experimentation of various folks. I think I read somewhere - and I could be wrong here - was that Uniden really didn't want folks to figure this out, hence the silence.
A file on how the filters seem to operate, and a link to the many discussions on this topic, can be found in our SDS FAQ, viz.
SDS100 and SDS200 FAQ Page - The RadioReference Wiki
Mike
It’s ok to ask a question!
Your question was are filters just for vhf/uhf.
To answer this No!
There are several types of filters, I will try to give you a description of what they do, first, a filter can be built or designed for any frequency, VLF, HF, VHF, UHF, Microwave frequencies and so on.
A Filter will either Pass through a certain tuned frequency and block everything above and below a pre tuned or pre engineered parameter, this is called a Bandpass filter, or BP filter.
Another type of filter will do just the opposite
It will reject a certain pre tuned or pre engineered frequency, this is called an Band reject or BR filter.
In speaking of radio receivers or scanners , manufacturers will sometimes provide various filter that is user selectable, to allow you to filter out unwanted distortion depending on what your receiving.
There are many types of filters to discuss, perhaps a wiki or google search will yield you a wealth of information on how various filters work as well as pictorials on what some of these arrangements look like.
Happy listening,
73’s
iMONITOR
Silent Key
Are you talking about the filters internal to the SDS100, or external filters that you put between the antenna and the radio?
Internal to the SDS100
I’m sorry, I was speaking externally with BP/BR type filters.
Just to show there are many types of filtering.
Different types of filters will filter different things.
Some mfg’s will build into to set different selectable filters to filter out distortion or unwanted interference depending on what type of monitoring your receiver is doing frequency wise, but there is also various types of audio filtering built onto many different receivers.
Just to show there are many types of filtering.
Different types of filters will filter different things.
Some mfg’s will build into to set different selectable filters to filter out distortion or unwanted interference depending on what type of monitoring your receiver is doing frequency wise, but there is also various types of audio filtering built onto many different receivers.
My guess is both, high pass and low pass are usually for isolating a particular frequency or bandwidth above and below, to attenuate the frequency or bandwidth or the just the opposite. But I believe the OP is talking about the filters available within the SDS100/200, which originally, were for use only by Uniden’s bench techs, and used primarily to understand the various issues related to simulcast. After Uniden began getting a lot of negative feedback from its end users (the consumers), they released the filtering accessibility, apparently in the hopes the end users would beta test them (without officially admitting to it) and solve the simulcast question. It follows when you consider the SDS radios were designed as an attempt to combat simulcast. Otherwise the BCDx36HP’s would have remained Uniden’s flagship radios. As best as I have determined, most all end users agree that the filter use is location dependent. Meaning you could be listening to the same system as your next door neighbor, both be bothered by simulcast and you would both come up with different filter settings as the best choice! In fact, moving the scanner equipped with the stock antenna a few inches may change which filter or no filter works best. I personally am not bothered by simulcast even though I have a few simulcast systems close. I consider myself lucky in that respect because if I was having a problem the general consensus in determining if a filter will help, which one, or none at all, requires all of the filters to be tried… a time consuming excersise to be sure.
There may be pushback on some of what I have observed, and while it may or may not be valid, the fact remains you still have to try all filters before you can decidedly determine which to use if any.
And that’s why there’s no definitive manual from Uniden on filter usage. But that old adage “Your results may vary.” Is what they should use.
paulears
Member
The most sensible comment was what Bill said. Filters are location specific. They are problem solvers or performance improvers. Here a notch at 153 is very handy from this location because from upstairs, I can see a pager tower, and it is mega strong, which has a very bad impact on marine band It's within the passband of the radios and saturates the front end, making weak signals just vanish. If you live twenty miles away, no filter needed. Looking at my analyser - there are really big spikes at all sorts of frequencies from services 'unhelpful' for scanner users. We also have the kind of filters in better quality radios so adjacent channel interference is better controlled.
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