BCD536HP: Proper step setting custom srch.

Status
Not open for further replies.

AlphaFive

Member
Joined
Apr 3, 2011
Messages
808
Location
1975
Okay, here is a head scratcher specific to a 536. Since I have nothing better to do I will ask people to take up their valuable time reading this....
Until very recently I would complete ' custom searches' in the following manner; I would choose a specific band I wanted in a 10 Mhz. block i.e. 400 to 410 Mhz. I would set 4 custom searches using a 5.0 step, 6.25 step, 7.50 step, and a 8.33 step. A few days ago I was studying the N.T.I.A. spectrum chart, a light bulb went off.
If the proper band in the area of the spectrum begins at 399.9000, which it does, and I start a 6.25 step at 400.12345 (ridiculous number but it makes a point), would not the 536 begin a search at 400.12345 and go up from that point 6.25 steps?? Thereby missing what would legitimately exist going up from a 399.9000 starting point. Or would somehow magically the 536 jump from 400.12345 to the next proper 6.25 step from 399.9000? I do not see how that would occur.
To make things worse, I just glanced at the specs for the 536 in that particular band. The unit stops at 399.9875, and picks up again at 400, even though the N.T.I.A. chart is slightly different. Now I'm not asking about this particular band at all..... I am totally curious about the step settings and whether they begin from a point that you set yourself,and not what would be a specification setting?
By the way, I use different step settings just to see if something is hiding out there, I'm well aware of the authorized steps. It is good to be different.
 

jonwienke

More Info Coming Soon!
Premium Subscriber
Joined
Jul 18, 2014
Messages
13,014
Location
VA
You're wasting your time. Even if someone was using a weird step size, and were TXing on 460.00833 instead of 460.01250, you'd still pick it up. A 4KHz tuning error may result in occasional distortion, but it won't stop you from detecting the transmission.

And the convention is that the nominal TX frequency will be a whole-number multiple of the step size. 400.1000 will occupy bandwidth above and below the nominal frequency--while 400.1000 is the center of the channel, the channel starts at 400.09375, and goes to 400.00625.

Just search from 400-410MHz or whatever and let the scanner do its thing. You're totally overthinking this.
 

AlphaFive

Member
Joined
Apr 3, 2011
Messages
808
Location
1975
Steps

Excellent, that was good information.. and easy to understand. The technical side of my brain has been leaning toward that conclusion. But,,, the O.C.D. is on my other shoulder going "c'mon man, you never know what could be hiding in there". Thanks for you help, it makes sense
 

Ubbe

Member
Joined
Sep 8, 2006
Messages
5,508
Location
Stockholm, Sweden
Uniden have a predefined raster it uses with different step sizes and you cannot fool it by making a start frequency that doesn't belong to the raster, it will follow the raster at the next step.

/Ubbe
 

AlphaFive

Member
Joined
Apr 3, 2011
Messages
808
Location
1975
Steps

Ahhh, that is interesting. Good for them, I can't mess the system up, no matter how much effort I put into it... This piece of information clears up a lot. Thank you.
 

kd7kdc

Completely Banned for the Greater Good
Banned
Joined
Jan 18, 2005
Messages
642
i have had to scratch my head on a new tait 220 mpt1327 system that went in a year or so ago.
the techs set the repeaters up on 6.25 channel centers and spaced those 12.5 apart.
i found out that both my uniden and radio shack scanners will start the count at whatever band edge you type in and the radio accepts. so i started the custom search on a 6.25kc freq and set the step to 12.5 and it works great.



Sent from my iPhone using Tapatalk
 

AlphaFive

Member
Joined
Apr 3, 2011
Messages
808
Location
1975
experiment

Okay, I conducted an experiment. I used four custom searches. 1st began at 400.000 (proper setting for the BCD536 to begin at), set at 5.00 step-- 2nd began at 400.123400, set at 5.00 step-- 3rd began at 400.000, set at 6.25 step-- 4th began at 400.123400, set at 6.25 step. I began the search, hit hold, and rolled the dail up from 400 to the next step while on hold.

1st search result - 400.000 to 400.0050, 400.0100, 400.0150
2nd search result - automatically began at 400.1250 to 400.1300, 400.1350, 400.1400
3rd search result - 400.000 to 400.0062, 400.01250, 400.0187
4th search result automatically began at 400.1250 to 400.1312, 400.1375, 400.1437
So, those of you with technical knowledge, which I do not possess, take this and run with it.. Thank you for your help, Lance

After doing some calculations, it appears that even if I try, I can't knock the 536 out of either a 5.00 step, or a 6.25 step of a proper frequency running up from 400.000, even beginning at 400.123400..hmm,
 
Last edited:
Status
Not open for further replies.
Top