Prev: Problems with Zadoff-Chu auto correlation
Next: Smartbook for DSP developer ?
From: Green Xenon on 14 Jan 2010 16:34
>Green Xenon wrote:
>>> Green Xenon wrote:
>>>>> Green Xenon wrote:
>>>>>>> Jerry Avins <jya(a)ieee.org> wrote:
>>>>>>> (snip)
>>>>>>>
>>>>>>>> Thanks.
>>>>>>>> You wrote in another post that 1 symbol/sec satisfies you. Since

>>>>>>>> sampling for a second theoretically yields 1 Hz resolution,
that's
>> a
>>>>>> lot
>>>>>>>> of frequencies in the telephone voice band. Using a spacing of 2
>> Hz
>>>> to
>>>>>>>> allow for less-than-ideal conditions, and taking the band to be
>> 300
>>>> to
>>>>>>>> 8,000 Hz, you can see that it is trivially simple to get 3,850
>> bits
>>>> in
>>>>>> a
>>>>>>>> symbol provided you can synchronize properly. Now, 2^3850 is a
big
>>
>>>>>>>> number, nearly 10^1159. What will you do with an alphabet of
that
>>>> many
>>>>>>>> letters?
>>>>>>> That should be 4kHz.
>>>>>>>
>>>>>>> Also, the bits/symbol is log2(number of possible symbols), so
>>>>>> log2(1850).
>>>>>>> Half the bandwidth might be enough to recover the clock. That
is,
>>>>>>> to know when the symbol transitions occur. There needs to be
>> enough
>>>>>>> (or sufficient) frequency changes such that the receiver can
detect
>>>>>>> where they occur, and not lose sync.
>>>>>>>
>>>>>>> A more efficient way is to use multiple BFSK carriers not
>> overlapping
>>>>>>> in frequency space. Then you do get a large number of bits.
>>>>>>>
>>>>>>> -- glen
>>>>>>>
>>>>>> According to http://www.motionnet.com/calculator/
>>>>>> log2(1850)=10.8533095554037
>>>>>>
>>>>>> 10.8533095554037 rounds off to 11.
>>>>> You can't fit 11 gallons into a 10.8533095554037-gallon can. Round
>> down.
>>>>>> Does this mean the max amount of bits-per-symbol using FSK on a
>> phone
>>>> line
>>>>>> is 11?
>>>>>>
>>>>>> What if I'm using a hypothetical FSK modem that does not require
>>>>>> additional power supply other than the electricity provided by the
>>>> phone
>>>>>> line itself? Then what is the maximum bits-per-symbol possible?
>>>>> Quote properly. You attribute some of Glenn's words to me. Glenn is

>>>>> right about the bandwidth, but we make different assumptions about
>>>>> counting bits. I assumed that every FFT bin could be counted as a
bit,
>>
>>>>> independently of the others, analogously to a bundle of wires which
>> can
>>>>> be energized in any combination. If you redo my calculation with the

>>>>> proper upper frequency and use half of that number to allow clock
>>>>> extraction, you still get a lot of bits through. Just as there's no
>> free
>>>>> lunch, it's possible to do things in unnecessarily complicated ways

>>>>> without losing capability. Ask Rube Goldberg.
>>>>>
>>>>> Jerry
>>>> I posted the message using
>>>> http://www.dsprelated.com/compdsppost.php?id=122814 replying to
Glenn
>> but
>>>> the website instead quoted you. Sorry about that.
>>>>
>>>> Anyways, so 10-bits-per-symbol is the max in the scenario I
describe?
>> As
>>>> asked before, what if the modems don't use any power supply other
than
>> the
>>>> phone line electric current, what would be the max bits-per-symbol,
>> then?
>>> The source of the modem's power doesn't affect the theoretical bit
rate.
>>
>>> The actual bit rate will depend on circuit design. The limit is set by

>>> thermodynamics, but we're not close to being limited by that.
>>>
>>> The phone line is capable of 64 Kb/sec in theory and 56 Kb/sec in
>>> practice. If you send a symbol per second, you can have 56 Kb/symbol.
If
>>
>>> you send a symbol per hour at 64 Kb/sec, you get 3.36
megabytes/symbol.
>>>
>>> Jerry
>
>> Really? It's possible to convey 56,000-bits-per-symbol on a phone line
>> using FSK [assuming a baud of 1-symbol-per-second]?
>>
>> Isn't their a limit to the amount of bits-per-symbol regardless of the
>> amount of symbols per second?
>>
>> From what your saying, it should be theoretically-possible [using FSK]
to
>> send a Graham's-number-of-bits-per-symbol on a phone line if the
symbol
>> rate is low enough.
>>
>> Graham's number is one extremely large number!
>
>Given a bit rate, the number of bits that ban be sent in a specified
>interval is easily calculated. If you wait long enough, you can collect
>as many bits as you want. You may, if you please, call the aggregate of
>those bits a symbol, or you may divide them into groups and call each of

>those groups a symbol. Typically, we group together 8 bits and call that

>an extended ASCII symbol. Certain clever signaling methods, QPSK, for
>example, send several bits simultaneously. For those methods, each
>distinguishable modulator output is also referred to as a symbol. You
>shouldn't confuse those two usages. Is that your problem?
>
>Jerry
>--
>Engineering is the art of making what you want from things you can get.
>�����������������������������������������������������������������������
>

I using the term "symbol" as it is defined here:

1. http://en.wikipedia.org/wiki/Symbol_rate

and

2. http://en.wikipedia.org/wiki/Baud

Given the above definition of "symbol", what is the maximum theoretical
and practical amount of bits-per-symbol possible using a phone line
assuming the modulation is FSK and the baud is only 1-symbol-per-second?

Are you sure this limit will be the same if the modem being used does not
require any power supply other than the electricity from the phone line
itself? I ask because I think processing more bits-per-symbol [assuming a
constant baud] will require more power.
From: Green Xenon on 20 Jan 2010 21:46
>Green Xenon wrote:
>>> Green Xenon wrote:
>>>>> Green Xenon wrote:
>>>>>>> Green Xenon wrote:
>>>>>>>>> Jerry Avins <jya(a)ieee.org> wrote:
>>>>>>>>> (snip)
>>>>>>>>>
>>>>>>>>>> Thanks.
>>>>>>>>>> You wrote in another post that 1 symbol/sec satisfies you.
Since
>>
>>>>>>>>>> sampling for a second theoretically yields 1 Hz resolution,
>> that's
>>>> a
>>>>>>>> lot
>>>>>>>>>> of frequencies in the telephone voice band. Using a spacing of
2
>>>> Hz
>>>>>> to
>>>>>>>>>> allow for less-than-ideal conditions, and taking the band to
be
>>>> 300
>>>>>> to
>>>>>>>>>> 8,000 Hz, you can see that it is trivially simple to get 3,850
>>>> bits
>>>>>> in
>>>>>>>> a
>>>>>>>>>> symbol provided you can synchronize properly. Now, 2^3850 is a
>> big
>>>>>>>>>> number, nearly 10^1159. What will you do with an alphabet of
>> that
>>>>>> many
>>>>>>>>>> letters?
>>>>>>>>> That should be 4kHz.
>>>>>>>>>
>>>>>>>>> Also, the bits/symbol is log2(number of possible symbols), so
>>>>>>>> log2(1850).
>>>>>>>>> Half the bandwidth might be enough to recover the clock. That
>> is,
>>>>>>>>> to know when the symbol transitions occur. There needs to be
>>>> enough
>>>>>>>>> (or sufficient) frequency changes such that the receiver can
>> detect
>>>>>>>>> where they occur, and not lose sync.
>>>>>>>>>
>>>>>>>>> A more efficient way is to use multiple BFSK carriers not
>>>> overlapping
>>>>>>>>> in frequency space. Then you do get a large number of bits.
>>>>>>>>>
>>>>>>>>> -- glen
>>>>>>>>>
>>>>>>>> According to http://www.motionnet.com/calculator/
>>>>>>>> log2(1850)=10.8533095554037
>>>>>>>>
>>>>>>>> 10.8533095554037 rounds off to 11.
>>>>>>> You can't fit 11 gallons into a 10.8533095554037-gallon can.
Round
>>>> down.
>>>>>>>> Does this mean the max amount of bits-per-symbol using FSK on a
>>>> phone
>>>>>> line
>>>>>>>> is 11?
>>>>>>>>
>>>>>>>> What if I'm using a hypothetical FSK modem that does not require
>>>>>>>> additional power supply other than the electricity provided by
the
>>>>>> phone
>>>>>>>> line itself? Then what is the maximum bits-per-symbol possible?
>>>>>>> Quote properly. You attribute some of Glenn's words to me. Glenn
is
>>
>>>>>>> right about the bandwidth, but we make different assumptions about

>>>>>>> counting bits. I assumed that every FFT bin could be counted as a
>> bit,
>>>>>>> independently of the others, analogously to a bundle of wires
which
>>>> can
>>>>>>> be energized in any combination. If you redo my calculation with
the
>>
>>>>>>> proper upper frequency and use half of that number to allow clock

>>>>>>> extraction, you still get a lot of bits through. Just as there's
no
>>>> free
>>>>>>> lunch, it's possible to do things in unnecessarily complicated
ways
>>
>>>>>>> without losing capability. Ask Rube Goldberg.
>>>>>>>
>>>>>>> Jerry
>>>>>> I posted the message using
>>>>>> http://www.dsprelated.com/compdsppost.php?id=122814 replying to
>> Glenn
>>>> but
>>>>>> the website instead quoted you. Sorry about that.
>>>>>>
>>>>>> Anyways, so 10-bits-per-symbol is the max in the scenario I
>> describe?
>>>> As
>>>>>> asked before, what if the modems don't use any power supply other
>> than
>>>> the
>>>>>> phone line electric current, what would be the max
bits-per-symbol,
>>>> then?
>>>>> The source of the modem's power doesn't affect the theoretical bit
>> rate.
>>>>> The actual bit rate will depend on circuit design. The limit is set
by
>>
>>>>> thermodynamics, but we're not close to being limited by that.
>>>>>
>>>>> The phone line is capable of 64 Kb/sec in theory and 56 Kb/sec in
>>>>> practice. If you send a symbol per second, you can have 56
Kb/symbol.
>> If
>>>>> you send a symbol per hour at 64 Kb/sec, you get 3.36
>> megabytes/symbol.
>>>>> Jerry
>>>> Really? It's possible to convey 56,000-bits-per-symbol on a phone
line
>>>> using FSK [assuming a baud of 1-symbol-per-second]?
>>>>
>>>> Isn't their a limit to the amount of bits-per-symbol regardless of
the
>>>> amount of symbols per second?
>>>>
>>>> From what your saying, it should be theoretically-possible [using
FSK]
>> to
>>>> send a Graham's-number-of-bits-per-symbol on a phone line if the
>> symbol
>>>> rate is low enough.
>>>>
>>>> Graham's number is one extremely large number!
>>> Given a bit rate, the number of bits that ban be sent in a specified
>>> interval is easily calculated. If you wait long enough, you can
collect
>>> as many bits as you want. You may, if you please, call the aggregate
of
>>> those bits a symbol, or you may divide them into groups and call each
of
>>
>>> those groups a symbol. Typically, we group together 8 bits and call
that
>>
>>> an extended ASCII symbol. Certain clever signaling methods, QPSK, for

>>> example, send several bits simultaneously. For those methods, each
>>> distinguishable modulator output is also referred to as a symbol. You

>>> shouldn't confuse those two usages. Is that your problem?
>>>
>>> Jerry
>>> --
>>> Engineering is the art of making what you want from things you can
get.
>>>
�����������������������������������������������������������������������
>>>
>>
>> I using the term "symbol" as it is defined here:
>>
>> 1. http://en.wikipedia.org/wiki/Symbol_rate
>>
>> and
>>
>> 2. http://en.wikipedia.org/wiki/Baud
>>
>> Given the above definition of "symbol", what is the maximum
theoretical
>> and practical amount of bits-per-symbol possible using a phone line
>> assuming the modulation is FSK and the baud is only
1-symbol-per-second?
>>
>> Are you sure this limit will be the same if the modem being used does
not
>> require any power supply other than the electricity from the phone
line
>> itself? I ask because I think processing more bits-per-symbol [assuming
a
>> constant baud] will require more power.
>
>The power depends on the technology. Tubes require about one watt apiece

>just for heater power. The plate circuit typically uses another 2 watts.

>Each tube replaces one transistor.
>
>jerry
>--
>Engineering is the art of making what you want from things you can get.
>�����������������������������������������������������������������������
>

How many watts required to process, transmit, receive 10-bits-per-symbol
FSK if transistors are used? Is the power from the phone line enough for
this?
From: Green Xenon on 21 Jan 2010 00:16
>Green Xenon wrote:
>>> Green Xenon wrote:
>>>>> Green Xenon wrote:
>>>>>>> Green Xenon wrote:
>>>>>>>>> Green Xenon wrote:
>>>>>>>>>>> Jerry Avins <jya(a)ieee.org> wrote:
>>>>>>>>>>> (snip)
>>>>>>>>>>>
>>>>>>>>>>>> Thanks.
>>>>>>>>>>>> You wrote in another post that 1 symbol/sec satisfies you.
>> Since
>>>>>>>>>>>> sampling for a second theoretically yields 1 Hz resolution,
>>>> that's
>>>>>> a
>>>>>>>>>> lot
>>>>>>>>>>>> of frequencies in the telephone voice band. Using a spacing
of
>> 2
>>>>>> Hz
>>>>>>>> to
>>>>>>>>>>>> allow for less-than-ideal conditions, and taking the band to
>> be
>>>>>> 300
>>>>>>>> to
>>>>>>>>>>>> 8,000 Hz, you can see that it is trivially simple to get
3,850
>>>>>> bits
>>>>>>>> in
>>>>>>>>>> a
>>>>>>>>>>>> symbol provided you can synchronize properly. Now, 2^3850 is
a
>>>> big
>>>>>>>>>>>> number, nearly 10^1159. What will you do with an alphabet of
>>>> that
>>>>>>>> many
>>>>>>>>>>>> letters?
>>>>>>>>>>> That should be 4kHz.
>>>>>>>>>>>
>>>>>>>>>>> Also, the bits/symbol is log2(number of possible symbols), so
>>>>>>>>>> log2(1850).
>>>>>>>>>>> Half the bandwidth might be enough to recover the clock.
That
>>>> is,
>>>>>>>>>>> to know when the symbol transitions occur. There needs to be
>>>>>> enough
>>>>>>>>>>> (or sufficient) frequency changes such that the receiver can
>>>> detect
>>>>>>>>>>> where they occur, and not lose sync.
>>>>>>>>>>>
>>>>>>>>>>> A more efficient way is to use multiple BFSK carriers not
>>>>>> overlapping
>>>>>>>>>>> in frequency space. Then you do get a large number of bits.
>>>>>>>>>>>
>>>>>>>>>>> -- glen
>>>>>>>>>>>
>>>>>>>>>> According to http://www.motionnet.com/calculator/
>>>>>>>>>> log2(1850)=10.8533095554037
>>>>>>>>>>
>>>>>>>>>> 10.8533095554037 rounds off to 11.
>>>>>>>>> You can't fit 11 gallons into a 10.8533095554037-gallon can.
>> Round
>>>>>> down.
>>>>>>>>>> Does this mean the max amount of bits-per-symbol using FSK on
a
>>>>>> phone
>>>>>>>> line
>>>>>>>>>> is 11?
>>>>>>>>>>
>>>>>>>>>> What if I'm using a hypothetical FSK modem that does not
require
>>>>>>>>>> additional power supply other than the electricity provided by
>> the
>>>>>>>> phone
>>>>>>>>>> line itself? Then what is the maximum bits-per-symbol
possible?
>>>>>>>>> Quote properly. You attribute some of Glenn's words to me.
Glenn
>> is
>>>>>>>>> right about the bandwidth, but we make different assumptions
about
>>
>>>>>>>>> counting bits. I assumed that every FFT bin could be counted as
a
>>>> bit,
>>>>>>>>> independently of the others, analogously to a bundle of wires
>> which
>>>>>> can
>>>>>>>>> be energized in any combination. If you redo my calculation
with
>> the
>>>>>>>>> proper upper frequency and use half of that number to allow
clock
>>
>>>>>>>>> extraction, you still get a lot of bits through. Just as
there's
>> no
>>>>>> free
>>>>>>>>> lunch, it's possible to do things in unnecessarily complicated
>> ways
>>>>>>>>> without losing capability. Ask Rube Goldberg.
>>>>>>>>>
>>>>>>>>> Jerry
>>>>>>>> I posted the message using
>>>>>>>> http://www.dsprelated.com/compdsppost.php?id=122814 replying to
>>>> Glenn
>>>>>> but
>>>>>>>> the website instead quoted you. Sorry about that.
>>>>>>>>
>>>>>>>> Anyways, so 10-bits-per-symbol is the max in the scenario I
>>>> describe?
>>>>>> As
>>>>>>>> asked before, what if the modems don't use any power supply
other
>>>> than
>>>>>> the
>>>>>>>> phone line electric current, what would be the max
>> bits-per-symbol,
>>>>>> then?
>>>>>>> The source of the modem's power doesn't affect the theoretical
bit
>>>> rate.
>>>>>>> The actual bit rate will depend on circuit design. The limit is
set
>> by
>>>>>>> thermodynamics, but we're not close to being limited by that.
>>>>>>>
>>>>>>> The phone line is capable of 64 Kb/sec in theory and 56 Kb/sec in

>>>>>>> practice. If you send a symbol per second, you can have 56
>> Kb/symbol.
>>>> If
>>>>>>> you send a symbol per hour at 64 Kb/sec, you get 3.36
>>>> megabytes/symbol.
>>>>>>> Jerry
>>>>>> Really? It's possible to convey 56,000-bits-per-symbol on a phone
>> line
>>>>>> using FSK [assuming a baud of 1-symbol-per-second]?
>>>>>>
>>>>>> Isn't their a limit to the amount of bits-per-symbol regardless of
>> the
>>>>>> amount of symbols per second?
>>>>>>
>>>>>> From what your saying, it should be theoretically-possible [using
>> FSK]
>>>> to
>>>>>> send a Graham's-number-of-bits-per-symbol on a phone line if the
>>>> symbol
>>>>>> rate is low enough.
>>>>>>
>>>>>> Graham's number is one extremely large number!
>>>>> Given a bit rate, the number of bits that ban be sent in a specified

>>>>> interval is easily calculated. If you wait long enough, you can
>> collect
>>>>> as many bits as you want. You may, if you please, call the
aggregate
>> of
>>>>> those bits a symbol, or you may divide them into groups and call
each
>> of
>>>>> those groups a symbol. Typically, we group together 8 bits and call
>> that
>>>>> an extended ASCII symbol. Certain clever signaling methods, QPSK,
for
>>
>>>>> example, send several bits simultaneously. For those methods, each
>>>>> distinguishable modulator output is also referred to as a symbol.
You
>>
>>>>> shouldn't confuse those two usages. Is that your problem?
>>>>>
>>>>> Jerry
>>>>> --
>>>>> Engineering is the art of making what you want from things you can
>> get.
>>
�����������������������������������������������������������������������
>>>> I using the term "symbol" as it is defined here:
>>>>
>>>> 1. http://en.wikipedia.org/wiki/Symbol_rate
>>>>
>>>> and
>>>>
>>>> 2. http://en.wikipedia.org/wiki/Baud
>>>>
>>>> Given the above definition of "symbol", what is the maximum
>> theoretical
>>>> and practical amount of bits-per-symbol possible using a phone line
>>>> assuming the modulation is FSK and the baud is only
>> 1-symbol-per-second?
>>>> Are you sure this limit will be the same if the modem being used
does
>> not
>>>> require any power supply other than the electricity from the phone
>> line
>>>> itself? I ask because I think processing more bits-per-symbol
[assuming
>> a
>>>> constant baud] will require more power.
>>> The power depends on the technology. Tubes require about one watt
apiece
>>
>>> just for heater power. The plate circuit typically uses another 2
watts.
>>
>>> Each tube replaces one transistor.
>>>
>>> jerry
>>> --
>>> Engineering is the art of making what you want from things you can
get.
>>>
�����������������������������������������������������������������������
>>>
>>
>> How many watts required to process, transmit, receive
10-bits-per-symbol
>> FSK if transistors are used? Is the power from the phone line enough
for
>> this?
>


>What kind of transistors?
>How large?
>What geometry?
>What year?

>The
>necessary power becomes less as technology improves.

What if the most advanced type of transistors are used?

>How much power can
>you use from the phone line? Lamps lit by it give enough light to read
by.

The amount of power necessary to light a lamp will cause the phone line to
stop working. There is a strict limit to how many watts one can consume
through the phone line. Once exceeded, the line automatically shuts-off.
First  |  Prev  | 
Pages: 1 2 3 4 5 6 7
Prev: Problems with Zadoff-Chu auto correlation
Next: Smartbook for DSP developer ?