RadioBanter

RadioBanter (https://www.radiobanter.com/)
-   Homebrew (https://www.radiobanter.com/homebrew/)
-   -   Field Strength (https://www.radiobanter.com/homebrew/21879-field-strength.html)

Paul Burridge December 15th 03 12:22 PM

On Mon, 15 Dec 2003 07:16:35 GMT, Active8
,invalid wrote:

Yes, but I thought the 40MHz project was *not* bot related.


Nope. *All* the 40Mhz stuff I post about is 'bot related. That's the
r/c band we're permitted to use. There's an alternative option to use
something up in UHF but I'm giving that a miss for obvious reasons.
:-)
--

"I expect history will be kind to me, since I intend to write it."
- Winston Churchill

Active8 December 15th 03 02:22 PM

On Mon, 15 Dec 2003 12:22:27 +0000,
said...
On Mon, 15 Dec 2003 07:16:35 GMT, Active8
,invalid wrote:

Yes, but I thought the 40MHz project was *not* bot related.


Nope. *All* the 40Mhz stuff I post about is 'bot related. That's the
r/c band we're permitted to use. There's an alternative option to use
something up in UHF but I'm giving that a miss for obvious reasons.
:-)

you'd **** if you knew how easy it can be to do a UHF radio with an
RFIC, but I'm not sure you're permitted to use the same modulation
methods. Hell, you can get a pre-approved module for $100. FSK -
you can use that! isn't you're deal PPM FSK? or PCM FSK?

BRs,
Mike

Active8 December 15th 03 02:22 PM

On Mon, 15 Dec 2003 12:22:27 +0000,
said...
On Mon, 15 Dec 2003 07:16:35 GMT, Active8
,invalid wrote:

Yes, but I thought the 40MHz project was *not* bot related.


Nope. *All* the 40Mhz stuff I post about is 'bot related. That's the
r/c band we're permitted to use. There's an alternative option to use
something up in UHF but I'm giving that a miss for obvious reasons.
:-)

you'd **** if you knew how easy it can be to do a UHF radio with an
RFIC, but I'm not sure you're permitted to use the same modulation
methods. Hell, you can get a pre-approved module for $100. FSK -
you can use that! isn't you're deal PPM FSK? or PCM FSK?

BRs,
Mike

Active8 December 15th 03 02:55 PM

On Mon, 15 Dec 2003 06:59:36 GMT, said...
Michael A. Terrell wrote:

Your web site is very hard to read with the dark blue background and
black text. A lot of people have vision problems, and can not read this
color combination.


Sorry. The next time I update it I'll see if I can find a better color.
I think I noticed that once while I was developing it - I think it is
due to a low-color VGA mode. I spent too long fooling around trying to
develop the fractal-smith chart background (thanks to da GIMP) to mess
with it any further. You can always edit the HTML yourself and change my
background color. Its not like I've got advertisers paying me.


I missed that. For my snith chart program. I wrote out the eqs for
intersecting circles, coded the graphics in VBA, and captured them
as bmps for the C++ version af the app.

I'll be damned. Thar's fractal impedance admittance charts in them
thar backgrounds!

Mike

Active8 December 15th 03 02:55 PM

On Mon, 15 Dec 2003 06:59:36 GMT, said...
Michael A. Terrell wrote:

Your web site is very hard to read with the dark blue background and
black text. A lot of people have vision problems, and can not read this
color combination.


Sorry. The next time I update it I'll see if I can find a better color.
I think I noticed that once while I was developing it - I think it is
due to a low-color VGA mode. I spent too long fooling around trying to
develop the fractal-smith chart background (thanks to da GIMP) to mess
with it any further. You can always edit the HTML yourself and change my
background color. Its not like I've got advertisers paying me.


I missed that. For my snith chart program. I wrote out the eqs for
intersecting circles, coded the graphics in VBA, and captured them
as bmps for the C++ version af the app.

I'll be damned. Thar's fractal impedance admittance charts in them
thar backgrounds!

Mike

Spajky December 16th 03 02:28 PM

On Sun, 14 Dec 2003 06:31:14 GMT, "Michael A. Terrell"
wrote:

Some
websites are a royal pain. I recently ran into an electronics
distributor who put their entire website in "Flash". There is no way I
will wait five minutes or more per page to download and run stupid
animation when I am looking for parts.


I share your opinion completelly; I hate Flash made sites & banners,
but not downlodable fun stuff in Flash ... /like jokes/ :-)

-- Regards, SPAJKY
& visit site - http://www.spajky.vze.com
Celly-III OC-ed,"Tualatin on BX-Slot1-MoBo!"
E-mail AntiSpam: remove ##

Spajky December 16th 03 02:28 PM

On Sun, 14 Dec 2003 06:31:14 GMT, "Michael A. Terrell"
wrote:

Some
websites are a royal pain. I recently ran into an electronics
distributor who put their entire website in "Flash". There is no way I
will wait five minutes or more per page to download and run stupid
animation when I am looking for parts.


I share your opinion completelly; I hate Flash made sites & banners,
but not downlodable fun stuff in Flash ... /like jokes/ :-)

-- Regards, SPAJKY
& visit site - http://www.spajky.vze.com
Celly-III OC-ed,"Tualatin on BX-Slot1-MoBo!"
E-mail AntiSpam: remove ##

Spajky December 16th 03 02:28 PM

On Sun, 14 Dec 2003 03:18:35 GMT, Active8
,invalid wrote:
Refresh my ram.


| E(uV/m) |
V (dBmV) = 20log | --------- / 1000 |
| 0.021f(MHz) |

plus correction for distance (regulations for limits are for
specific measuring distances), etc. I'll mull the above eq over.
Gotta figure out where the .021 came from, but not now.


I use simplified formula for practical life with also some antenna
mismatchings & soft obstacles in-calculated:

dBm = ~90dB x 1Mhz x 1km or better dBm = 100dB x 1Mhz x 1km
for having better Rx SINAD

since voltage on Rx antenna drops linearly with rising a frequency &
distance & vice-versa. From dBm´s got I just recalculate RX voltage on
RX input

simple & effective calculation IMHO ...





-- Regards, SPAJKY
& visit site - http://www.spajky.vze.com
Celly-III OC-ed,"Tualatin on BX-Slot1-MoBo!"
E-mail AntiSpam: remove ##

Spajky December 16th 03 02:28 PM

On Sun, 14 Dec 2003 03:18:35 GMT, Active8
,invalid wrote:
Refresh my ram.


| E(uV/m) |
V (dBmV) = 20log | --------- / 1000 |
| 0.021f(MHz) |

plus correction for distance (regulations for limits are for
specific measuring distances), etc. I'll mull the above eq over.
Gotta figure out where the .021 came from, but not now.


I use simplified formula for practical life with also some antenna
mismatchings & soft obstacles in-calculated:

dBm = ~90dB x 1Mhz x 1km or better dBm = 100dB x 1Mhz x 1km
for having better Rx SINAD

since voltage on Rx antenna drops linearly with rising a frequency &
distance & vice-versa. From dBm´s got I just recalculate RX voltage on
RX input

simple & effective calculation IMHO ...





-- Regards, SPAJKY
& visit site - http://www.spajky.vze.com
Celly-III OC-ed,"Tualatin on BX-Slot1-MoBo!"
E-mail AntiSpam: remove ##

Active8 December 16th 03 11:16 PM

On Mon, 15 Dec 2003 06:59:30 GMT, said...
Paul Burridge wrote:

I'll add that my Optoelectronics handi-counter's fsm bargraph can detect
a few hundred milliwatts at several feet away.

I visualize a radio-field power density being grid-lines painted on a
balloon around a 1/2 wave dipole. As the balloon is blown up, the
grid-line expand, given by 4 pi r^2.

For some good app notes on designing electrically small antennas and
radio link calculations:

Goto -
http://www.rfm.com/corp/apnotes.htm

Checkout:
http://www.rfm.com/corp/appdata/antenna.pdf
http://www.rfm.com/products/tr_des24.pdf

HP (now Agilent) has some app-notes on designing diode detectors, and
has some utility programs that will help you design and calculate
performance. Some I think, in context of RFID reading devices. But they
point out you get a square-law for small signals, which gets nonlinear
for larger signal levels. And what bias the detector diode has on it.



Any particular search string to use for that Agilent stuff? They're
usually good for info on stuff like that.

Mike


All times are GMT +1. The time now is 09:07 PM.

Powered by vBulletin® Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
RadioBanter.com