[Ronja] 100 mbps FSO
Pramod yaduvanshi
pkyaduvanshi at gmail.com
Fri Feb 22 14:33:12 GMT 2008
Dear Kevin ,
I will just have a look at MAX3766 and see if i can modify my schematics . I
was looking for a good limiter and as suggested by Eldis i will try and use
MAX3657 for TIA, and MAX3645 because Philips is not ready to supply me
samples and haven't seen any cheap limiter from Philips.
My Schematics for ML6652 are already ready just few modifications are needed
and will try to use the new components as suggested by Eldis and you . Why
i went for ML6652 is because they have already sent me four samples ... so
don't want to even look at other Media converters.
By the way my luxeon star Tx/Rx with 350mA drive current is working
perfectly as desired and I have put a heat sink for the LED . Clock had
objected to the coaxial from the IC to LED but i measured the impedance of
the cable on Network analyser and its inductance is zero so i am not
planning to remove it since it makes making optical head much simpler . Will
be uplodaing the pictures of my Transmitter and Optical head on my blod
tonight for others to have a look.
Looking forward for more comments
PK Yaduvanshi
On 22/02/2008, Kevin Bortis <wermut at gmail.com> wrote:
>
> Hi Yaduvanshi,
>
> Please consider the MAX3766 instead of the MAX3263, because the
> MAX3263 has reached end of life.
>
> Regards
>
> On 2/22/08, Pramod yaduvanshi <pkyaduvanshi at gmail.com> wrote:
> > I am working on a 100 mbps design based on ML6652 and LED driver is
> MAX3263
> > and Reciver uses philips SA5211 as transimpedance Amplifier .Will be
> > releasing first shematics in a day or two . I am planning to use VCSEL
> laser
> > to begin with .
> >
> > Since ML6652 has autonegotiation feature all those will be no problem
> for
> > 100mbps design . Only problem will be soldering ML6652 which will need
> > specail facility and might not be possible in a home lab .
> >
> > PK Yaduvanshi
> >
> >
> > On 22/02/2008, ronja-request at lists.pointless.net
> > <ronja-request at lists.pointless.net> wrote:
> > > Send Ronja mailing list submissions to
> > > ronja at lists.pointless.net
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> > > than "Re: Contents of Ronja digest..."
> > >
> > >
> > > Today's Topics:
> > >
> > > 1. Re: What is holding back 100 mbps (J.D. Bakker)
> > > 2. Re: What is holding back 100 mbps (J.D. Bakker)
> > > 3. Re: What is holding back 100 mbps (Pavel Krejci)
> > > 4. Re: What is holding back 100 mbps (Thomas Egenhofer)
> > > 5. Re: What is holding back 100 mbps (Gregory Maxwell)
> > > 6. Re: What is holding back 100 mbps (J.D. Bakker)
> > > 7. Re: What is holding back 100 mbps (Daniel Strnad)
> > > 8. Re: What is holding back 100 mbps (Gregory Maxwell)
> > > 9. Re: What is holding back 100 mbps (alex dinovitser)
> > >
> > >
> > >
> > ----------------------------------------------------------------------
> > >
> > > Message: 1
> > > Date: Thu, 21 Feb 2008 13:11:00 +0100
> > > From: "J.D. Bakker" <jdb at lartmaker.nl>
> > > Subject: Re: [Ronja] What is holding back 100 mbps
> > > To: Twibright Ronja <ronja at lists.pointless.net>
> > > Message-ID: <p0624052ec3e31a35c4dd@[130.161.115.44]>
> > > Content-Type: text/plain; charset="us-ascii" ; format="flowed"
> > >
> > > >---- Deepak Mishra <xask.linus at gmail.com> schrieb:
> > > >> Hi people,
> > > >> 100 Mbps open source FSO, I think would revolutionize the wireless
> > link
> > > >> scene.
> > > >> I am really confused as to what is really holding back the
> development
> > of
> > > >> 100 Mbps RONJA, even when every thing is open source and free.
> > > >
> > > >The fact that I have to go to work? Anyone has resources to pay one
> > > >developer fulltime?
> > >
> > > What Clock said.
> > >
> > > I have a prototype PCB for a 100MHz RX/TX unit but simply have had no
> > > time to test/tweak/enhance it. LED fall time is the issue so far; I
> > > know what to do about it, but (payed) work takes precedence over a
> > > GPLed project.
> > >
> > > JDB
> > > [already have a kit/prebuilt boards deal set up with my commercial
> > > partners in Taiwan]
> > > --
> > > LART. 250 MIPS under one Watt. Free hardware design files.
> > > http://www.lartmaker.nl/
> > >
> > >
> > >
> > > ------------------------------
> > >
> > > Message: 2
> > > Date: Thu, 21 Feb 2008 13:19:11 +0100
> > > From: "J.D. Bakker" <jdb at lartmaker.nl>
> > > Subject: Re: [Ronja] What is holding back 100 mbps
> > > To: Twibright Ronja <ronja at lists.pointless.net>
> > > Message-ID: <p06240530c3e31c4d42ac@[130.161.115.44]>
> > > Content-Type: text/plain; charset="us-ascii" ; format="flowed"
> > >
> > > > > > I start this thread to exactly pin point the problems of a 100
> > > >Mbps RONJA.
> > > >> > Let us reach to a conclusion as to what exactly must be
> modified.
> > > >> >
> > > >> > Let us start with the LED,
> > > >> > 1. To transmit at 100 mbps,we must find an LED which can switch
> on
> > and off
> > > >> > in 1 ns.
> > > >that's not neccessariliy true. if you wanna use 2-level encoded
> > > >signals like now ,you'd run into several problems.
> > > >first is you would have to change the encoding of the MLT3 signal to
> > > >2-level signal which is suited for optical transmission. in easiest
> > > >case manchester code.
> > > >which would result in a 0.5ns signal-time.
> > >
> > > Why does a 100Mbit Manchester encoded signal (with 10ns per bit) have
> > > a 0.5ns signal-time? Methinks you are off by an order of magnitude.
> > >
> > > JDB
> > > [not that you'd want to use Manchester if you can help it...]
> > > --
> > > LART. 250 MIPS under one Watt. Free hardware design files.
> > > http://www.lartmaker.nl/
> > >
> > >
> > >
> > > ------------------------------
> > >
> > > Message: 3
> > > Date: Thu, 21 Feb 2008 19:06:14 +0100
> > > From: Pavel Krejci <krepa at seznam.cz>
> > > Subject: Re: [Ronja] What is holding back 100 mbps
> > > To: Twibright Ronja <ronja at lists.pointless.net>
> > > Message-ID: <47BDBD96.7030505 at seznam.cz>
> > > Content-Type: text/plain; charset="us-ascii"
> > >
> > > An HTML attachment was scrubbed...
> > > URL:
> >
> http://pointless.net/pipermail/ronja/attachments/20080221/9cc0d683/attachment-0001.html
> > >
> > > ------------------------------
> > >
> > > Message: 4
> > > Date: Thu, 21 Feb 2008 21:59:35 +0100
> > > From: Thomas Egenhofer <antitron at web.de>
> > > Subject: Re: [Ronja] What is holding back 100 mbps
> > > To: ronja at lists.pointless.net
> > > Message-ID:
> > <1203627575.4502.8.camel at localhost.localdomain>
> > > Content-Type: text/plain
> > >
> > >
> > > > Hi all,
> > > > The discussion so far
> > > >
> > > > Saad Shakeel says
> > > > 2. Need equally fast photodiode and 74xx ics
> > > > 3. faster ne592 alternate as it only works at 10nS
> > > > 4. we might be able to use the bf908 since it supports upto 1
> GHz.
> > > >
> > > > Thomas Egenhofer says
> > > > - Think over encoding technique
> > > > 1. 2 level encoding at 100 mbps could run into problems.
> > > > 2. 2 level encoding would require rise and fall times of .5ns !
> > > sorry.. looks like a zero shifted around in my brain. should be 5ns i
> > > think..
> > >
> > >
> > > > 3. MLT3, coming from the LAN card could be used (30ns),
> requiring in
> > > > rise and fall times of 15ns of LED
> > > > 4. It would require redesigning the transmitter
> > > i dont belive you can skipp this if used with 2level encoding^^ also
> > > keep in mind that signal-times of 10ns are quite tricky to handle.
> even
> > > fast logic can easily produce a delay of up to 15ns which can cause
> many
> > > problems with signal-timing in general.
> > >
> > > > 5. He already has a prototype MTL3 reciever at
> > > >
> > http://home.arcor.de/positiveelectron/files/MLT-3-receiver.png
> > > >
> > > > Meanwhile CD930 shows us he already has a 100 Mbps version, but alas
> the
> > in
> > > > the clutches of proprietary license
> > > > He has videos at
> > > > http://www.youtube.com/watch?v=9h3hDm32kv4
> > > > http://www.youtube.com/watch?v=YcjaJhMHcNk
> > > >
> > > > and even better people like Jim Thompson are waiting to be convinced
> to
> > > > finance a 100 Mbps version.
> > > >
> > > >
> > > > What are we waiting for ?
> > >
> > >
> > >
> > >
> > >
> > > ------------------------------
> > >
> > > Message: 5
> > > Date: Thu, 21 Feb 2008 16:06:35 -0500
> > > From: "Gregory Maxwell" <gmaxwell at gmail.com>
> > > Subject: Re: [Ronja] What is holding back 100 mbps
> > > To: "Twibright Ronja" <ronja at lists.pointless.net>
> > > Message-ID:
> > >
> > <e692861c0802211306q5764399fuc5bd1e92bb70c18b at mail.gmail.com>
> > > Content-Type: text/plain; charset=UTF-8
> > >
> > > On Wed, Feb 20, 2008 at 4:20 PM, Thomas Egenhofer <antitron at web.de>
> wrote:
> > > [snip]
> > > > first is you would have to change the encoding of the MLT3 signal
> to
> > 2-level signal which is suited for optical transmission. in easiest case
> > manchester code.
> > >
> > > This makes no sense to me. Going to a higher encoding level should
> > > trade bandpass for SNR (and linearity) requirements.
> > >
> > > It might not be a huge win given the channel characteristics, but
> > > saying that it would need several orders of magnitude more bandwidth
> > > (which is what saying .5ns rise time is saying)
> > >
> > > With a proper EQ (which would be easy with an all digital
> > > modulator/demodulator) higher level encoding should work well across
> > > the optical channel.
> > >
> > >
> > >
> > > ------------------------------
> > >
> > > Message: 6
> > > Date: Thu, 21 Feb 2008 22:32:36 +0100
> > > From: "J.D. Bakker" <jdb at lartmaker.nl>
> > > Subject: Re: [Ronja] What is holding back 100 mbps
> > > To: Twibright Ronja <ronja at lists.pointless.net>
> > > Message-ID: <p06240535c3e39dc69b50@[130.161.115.44]>
> > > Content-Type: text/plain; charset="us-ascii" ; format="flowed"
> > >
> > > >With a proper EQ (which would be easy with an all digital
> > > >modulator/demodulator)
> > >
> > > In dedicated silicon or a larger FPGA, yes. In gates or discrete
> > > hardware, not so much.
> > >
> > > JDB
> > > [ran into this when designing a 100Mbps synchronizer, which is quite
> > > a bit easier than an EQ. For ASICs this is a solved problem, but I
> > > wanted/needed to do it in commercially available gates]
> > > --
> > > LART. 250 MIPS under one Watt. Free hardware design files.
> > > http://www.lartmaker.nl/
> > >
> > >
> > >
> > > ------------------------------
> > >
> > > Message: 7
> > > Date: Thu, 21 Feb 2008 22:35:39 +0100
> > > From: "Daniel Strnad" <daniel.strnad at tiscali.cz>
> > > Subject: Re: [Ronja] What is holding back 100 mbps
> > > To: "Twibright Ronja" <ronja at lists.pointless.net>
> > > Message-ID: <op.t6v8xpt2n6qjls at daman>
> > > Content-Type: text/plain; format=flowed; delsp=yes; charset=utf-8
> > >
> > > Hi all,
> > > I am not very interrested in topic for some time, but I have few fast,
> > > suitable for 100Mbps, photodiodes. I planned some design with it, but
> now
> > > I offer it for experiments to you. It's FCI-HR008
> > > (http://www.datasheetarchive.com/pdf/1382205.pdf). It has
> > capacitance
> > > 0.8pF at 5V! Price: 1 000CZK (40?) per piece.
> > >
> > > DS
> > >
> > >
> > >
> > > ------------------------------
> > >
> > > Message: 8
> > > Date: Thu, 21 Feb 2008 16:36:08 -0500
> > > From: "Gregory Maxwell" <gmaxwell at gmail.com>
> > > Subject: Re: [Ronja] What is holding back 100 mbps
> > > To: "Twibright Ronja" <ronja at lists.pointless.net>
> > > Message-ID:
> > >
> > <e692861c0802211336n22170588s79deb3def160857f at mail.gmail.com>
> > > Content-Type: text/plain; charset=UTF-8
> > >
> > > On Thu, Feb 21, 2008 at 4:32 PM, J.D. Bakker <jdb at lartmaker.nl> wrote:
> > > > >With a proper EQ (which would be easy with an all digital
> > > > >modulator/demodulator)
> > > >
> > > > In dedicated silicon or a larger FPGA, yes. In gates or discrete
> > > > hardware, not so much.
> > >
> > > Yes. mac->fpga->adc/dac->current amp. Solved. But making that
> > > inexpensive? ... :-/
> > >
> > >
> > >
> > > ------------------------------
> > >
> > > Message: 9
> > > Date: Thu, 21 Feb 2008 22:59:07 -0800 (PST)
> > > From: alex dinovitser <adinov at yahoo.com>
> > > Subject: Re: [Ronja] What is holding back 100 mbps
> > > To: Twibright Ronja <ronja at lists.pointless.net>
> > > Message-ID: <293348.55216.qm at web32708.mail.mud.yahoo.com>
> > > Content-Type: text/plain; charset=iso-8859-1
> > >
> > > This is surely analogous to the high speed fiber communications such
> as
> > DWDM.
> > > The current standard here is 10Gb/s per channel. That corresponds to
> an
> > > electrical bandwidth of at least 5GHz. These optical devices are
> specified
> > to
> > > 10GHz.
> > >
> > > The diodes required for this application need to have a very low
> > capacitance.
> > > This capacitance (almost) solely determines the speed of the resulting
> > > transimpedance amplifier.
> > > A diode's capacitance depends on its area. It also depends on the
> applied
> > > reverse voltage. However, it would be wrong to use and avalanche diode
> in
> > > avalanche mode! This diode detects individual photons, and each event
> has
> > a
> > > 'quench time' (it works very similar in principle to a geiger-muller
> tube)
> > > which means they will saturate with very low ambient light levels!
> > >
> > > Avalanche type diodes can be suitable if operated at lower voltage
> because
> > of
> > > their small area and a wide pIn channel that results in lower
> capacitance.
> > They
> > > are very expensive however.
> > >
> > > The small area for a suitably fast RONJA diode might requires some
> thought
> > of
> > > the optical system.
> > >
> > > I still think the best detector theoretically would be a pyroelectric
> > device.
> > > No suitable affortable devices so far:-(
> > >
> > >
> > > AD
> > >
> > >
> > > --- Pavel Krejci <krepa at seznam.cz> wrote:
> > >
> > >
> > > ---------------------------------
> > > Can you tell us, please, at least which chipset from MAXIM it is?
> > > Thanks
> > >
> > > PK
> > >
> > > CD930 napsal(a): Sorry...no, maybe later. But...TX,RXis MAXIM
> > chipset,
> > > mediaconvertor MARVELL 1108 (beforeused Micro-Linear), laser is
> > 870nm/10mW and
> > > photodiode is PDB-C102.
> > > Tested (tx lens 11cm, rx fresnellens 20cm) on 2500m. RSSI go to AD and
> > Atmel
> > > CPU (LCD and RS232c).
> > > M.
> > >
> > > -----Original Message -----
> > > From: Deepak Mishra
> > > To: Twibright Ronja
> > > Sent:Thursday, February 21, 2008 9:48 AM
> > > Subject:Re: [Ronja] What is holding back 100 mbps
> > >
> > >
> > > Hi CD930,
> > > Sure dont release the PCB, but you could give us suggestions
> onimproving
> > the
> > > RONJA design to 100 Mbps.
> > > You could point us in the right direction, like the
> modulationtechnique to
> > use,
> > > coding technique, or LED used ,or lasers, otherpitfalls you
> encountered ?
> > > Would you like to support a "free" cause ?
> > >
> > > Regards,
> > > Deepak
> > >
> > > On 21/02/2008, CD930 <cd930 at centrum.cz> wrote: HiVladimir.
> > > Sorry, this development was for one firm from our city.
> > > I must not publish circuit PCB :(
> > > But....some ideas i am here publish along the years.
> > >
> > > In future looking on 1Gpbs..... avalanche photodiode with 200V dc :)))
> > > roung again toy gadget.
> > >
> > > Martin
> > >
> > >
> > >
> > >
> > >
> > > ----- Original Message -----
> > > From: "Vladimir Obradovic" <lepiaf at bgwireless.net>
> > > To:
> > "ronja-request at lists.pointless.net"<ronja at lists.pointless.net>
> > > Sent: Thursday, February 21, 2008 1:35 AM
> > > Subject: Re: [Ronja] What is holding back 100 mbps
> > >
> > >
> > > >
> > >
> > > >> From: "CD930" <cd930 at centrum.cz>
> > > >> I tested on MAXIM and MARVELL chip-set....
> > > >> http://www.youtube.com/watch?v=9h3hDm32kv4
> > > >> http://www.youtube.com/watch?v=YcjaJhMHcNk
> > > >
> > > >> TX can by IR-LED, but with short peak to 1ns......
> > > >> http://www.roithner-laser.com/LED_MID_IR.htm or
> > > >> http://www.roithner-laser.com/LED_HP_single_chip.html
> > > >
> > > >> I am after tested go to laser diode, it is simply.
> > > >> Martin
> > > >
> > > > Nice demo Martin, is there some chance that documentation, tips or
> > > > howtos be available about this project some time in future? Anyplans
> > > > for some kind of open hardware licence like Ronja is, or it will be
> > > > yet another of those projects that inherit Ronja's ideas/hw,
> showsome
> > > > good
> > > > stuff and then go into some factory for big bucks only :) ? Nowonder
> > > > why Cl always gets upset when ppl start asking about 100mbps orxtra
> > > > range versions :)
> > > >
> > > > cya
> > > > LePiaf
> > > >
> > > >
> > > > --
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> > > > Ronja at lists.pointless.net
> > > > http://pointless.net/mailman/listinfo/ronja
> > > >
> > > >
> > >
> > >
> > > --
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> > > Ronja at lists.pointless.net
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> > >
> > >
> > >
> > >
> > >
> > > ---------------------------------
> > > --
> > > Twibright Ronja mailing list http://ronja.twibright.com
> > > Ronja at lists.pointless.net
> > > http://pointless.net/mailman/listinfo/ronja
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> > >
> > >
> > >
> > >
> >
> ____________________________________________________________________________________
> > > Never miss a thing. Make Yahoo your home page.
> > > http://www.yahoo.com/r/hs
> > >
> > >
> > >
> > > ------------------------------
> > >
> > > _______________________________________________
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> > >
> > > End of Ronja Digest, Vol 58, Issue 13
> > > *************************************
> > >
> >
> >
> >
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