Wind/Solar Electrics ???

Simple hetrodyne system will do that. No demodulating required.

in message

that's has all (of a

energy between 144-148MHz

recover everything.

you only have to sample

You can represent the bandwidth with double the sampling rate as the bandwidth frequency but there is a component missing from the sample information that has to be known and is not part of the samples. Namely the base frequency has to be added back into the formula.

bandwidth of 50 hz,

accurate reproduction?

that is important. The

band is at 0 hz

max frequency).

If only the baseband frequency is sampled at 6kHz then information is missing to recreate the original 100kHz and the sampling information is insufficient to recreate the original signal.

This is analogous to saying the number 1234 can be represented by (1234-234) / 1000 = 1

If I supply the number 1.0 you can regenerate the number 1234 from it? Not true, without the rest of the sampling information. The sample is incomplete.

Bandwidth sampling only cannot recreate the original signal.

,

wrote:

"daestrom"

wrote:

people stating something

least twice the highest

course it says no such thing.)

components of the input signal

tell them from lower

information' and not being able to

a low or high frequency

sample at least twice as fast

a bandwidth of 50 hz,

accurate reproduction?

that is important. The

the band is at 0 hz

the max frequency).

Nyquist requires that

when determining

BaseBand then only the

at baseband, then

determine samling

and the sampling is

If the sampling is

200.006 Mhz sampling

Frequencies, and if

Frequency, the easyier it

Only if you demodulate the signal first.

daestrom

So, if I have a signal with a 1000 hz carrier, with a bandwidth of 50 hz, you think I can sample it at just 150 hz and get accurate reproduction? That's just wrong.

It is the maximum frequency component in the signal that is important. The bandwidth is not related unless the lower edge of the band is at 0 hz (whereupon the upper side of the band is equal to the max frequency).

daestrom

Judging from your previous posts, I think you mean when you hear "Modified

*sine* wave", then you know you are dealing with shyster or an ignorant person...."

A salesperson that says their unit puts out a modified *square* wave would be a sign[sic] of a knowledgable salesperson.

daestrom

You are getting your terms confused here guys. Nyquist requires that you input both the Center Frequency, and Bandwidth when determining the Sampling Rate. If the sampling is done at BaseBand then only the Bandwidth is relevent. If the sampling is not done at baseband, then the Center Frequency, and Bandwidth are required to determine samling rate. Example, if the Bandwith of the signal is 3Kc and the sampling is done at BaseBand then sample rate needed would 6Kc. If the sampling is done at 100 Mhz with the same 3Kc bandwidth, then a 200.006 Mhz sampling rate would be required.

It is much easyier to do DSP at baseBand, than at IF Frequencies, and if you do DSP at IF Frequencies, the lower the IF Frequency, the easyier it is to do, and the slower the DSP has to run.

Me

He previously wrote about using either a 150 Ohm rheostat (other times referred to as 150A or 200A), or 300k nichrome wire to control a few Amps of field current on a small 12V automotive alternator. According to the "designer" (who often refers to himself as a "solar power consultant"), 150 Ohms didn't allow sufficiently low output, hence the need for the nichrome wire. And as we all know, the prime consideration on a home-power generator is low output. Similar wisdom surely underpins his other projects. For instance, liberal application of 300k wire might be useful when building a max 150, peak

300, zero Watt inverter, or most any zero Watt inverter for that matter. Perhaps strung around the property in large coils like razor wire at Slinky Manor. ;-)

Wayne

For the small and large stuff we used solid state SCRs while the intermediate still used saturable core reactors. 10 years ago I think they still had some mag amps, but the ones we had were pretty stable.

They use larger SCRs now, but I have the silicon wafer out of one that is over 1 1/2" in diameter. They operated up to 480 and 1000 Amps and ran near maximum for many hours. The SCRs themselves were about the size of a hockey puck or slightly larger.

Now there was some power and I'd guess they use much larger systems now.

Roger Halstead (K8RI & ARRL life member) (N833R, S# CD-2 Worlds oldest Debonair)

No, that's the whole point of this discussion.

You have to understand aliasing. The signal you want aliases down into the baseband. Your anti-aliaising filter has to get rid of all the junk you don't want. In this case it includes the baseband. Since there is no baseband signal (or other out-of-band junk) you can reconstruct the original signal.

It's a common trick with software radios.

You do need some extra information that doesn't go in through the A/D channel. That's the design of the system, in particular what the anti-aliasing filter lets through.

Maybe the reason that this is so confusing is that you also need that info the the normal/baseband case. But since that's the normal case we don't bother mentioning it.

--
The suespammers.org mail server is located in California.  So are all my
other mailboxes.  Please do not send unsolicited bulk e-mail or unsolicited
commercial e-mail to my suespammers.org address or any of my other addresses.
These are my opinions, not necessarily my employer\'s.  I hate spam.

Where is the baseband information stored if it isn't encoded into the sampling?

a bandwidth of 50 hz,

accurate reproduction?

aliases

has

case it

signal

original

through

particular

you also need

that's the normal

California. So are all my

e-mail or unsolicited

any of my other addresses.

I hate spam.

>

I'm not sure what you are asking.

If you have a 1 MHz carrier with 1 KHz of bandwidth, you might do something like sample at 10 KHz so your anti-alias filter has some room to work with. Then you feed the signal into a FFT and throw away the buckets that the filter didn't get rid of.

You often pick the sampling frequency so the FFT buckets (after aliasing) come out on convenient numbers.

If by "baseband" you mean the raw signal between 0 and X, there isn't any information between 0 and X-tiny in a typical narrow band modulated signal.

If you are doing the aliasing trick, the anti-aliasing filter has to block the baseband junk (noise) or it will get into the A/D and confuse things. It's the reverse of the "normal" anti-alias filter that gets rid of the noise above the baseband so it doesn't alias down and trash your signal.

--
The suespammers.org mail server is located in California.  So are all my
other mailboxes.  Please do not send unsolicited bulk e-mail or unsolicited
commercial e-mail to my suespammers.org address or any of my other addresses.
These are my opinions, not necessarily my employer\'s.  I hate spam.

OHMYGOD! A blunder admitted! Who the hell are you and what have you done with George Ghio?

Wayne

PS It's in everyone's best interest that you not be found out, so don't forget to hide your pod.

You too George.

Merry Christmas to Wayne and all his socks.

solar new year.

message

who will tell you anything

really getting.

dealing either with a shyster

things he does not

when you hear "Modified

shyster or an ignorant

modified *square* wave would

too many hours under

and what have you

be found out, so

The point is the sampling rate has to be done at just over double the frequency of the signal and not the bandwidth.

buckets

and X,

typical

anti-aliasing filter

into the

"normal" anti-alias

so it doesn't

California. So are all my

e-mail or unsolicited

any of my other addresses.

I hate spam.

>

I'm sorry that I'm not smart enough to describe it in a way that you can understand.

Maybe if you google for software-radio you will find something that explains it in a way that makes sense.

--
The suespammers.org mail server is located in California.  So are all my
other mailboxes.  Please do not send unsolicited bulk e-mail or unsolicited
commercial e-mail to my suespammers.org address or any of my other addresses.
These are my opinions, not necessarily my employer\'s.  I hate spam.