[Ronja] Ronja Digest, Vol 58, Issue 13
Pramod yaduvanshi
pkyaduvanshi at gmail.com
Fri Feb 22 08:24:37 GMT 2008
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:
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> 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"
>
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> ------------------------------
>
> 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
> >
> >
> > --
> > Twibright Ronja mailing list http://ronja.twibright.com
> > Ronja at lists.pointless.net
> > http://pointless.net/mailman/listinfo/ronja
> >
> >
>
>
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> End of Ronja Digest, Vol 58, Issue 13
> *************************************
>
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