Doing a 5Gbps transmission is doable these days but a bit of a challenge. He'd have to digitize somewhere around 400MSPS, times 10 bits plus some sync overhead.
Why that high? I bet John would spring for more than an RC lowpass here :-)
He needs only 150MHz signal bandwidth.
Well, yeah, it would have to be some, as John called it, one-shot on steroids. This will not be very accurate and linear so it needs to be servoed at the transmitter. The loop filter in that servo won't exactly be trivial but looking at their product portfolio just about everything they build pushes the envelope a bit farther.
--
Regards, Joerg
http://www.analogconsultants.com/
"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
This is where experiments come in. Lots of stuff such as LD behavior just cannot be modeled, on my first laser project I learned rather quickly to hang up those efforts and flipped the switch on the Weller.
Same goes for the photodiode. Ok, we needed less than half of John's BW and used phase modulation but at a heck of a lot more than 10bits worth of dynamic range. And we got it.
As long as it doesn't spit out the cleaning tape like ours kept doing yesterday. Looks like another weekend honey-do project :-(
--
Regards, Joerg
http://www.analogconsultants.com/
"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
On a sunny day (Tue, 13 Jul 2010 14:10:46 -0700) it happened Joerg wrote in :
I digitised my VHS tapes about ten years ago. If you care about any of your videos you should do the same, and put the VHS with the trash. Some people claim tapes last longer then DVDs .. But I have seen too many damaged tapes and dropouts. If yoy digitise with the PC, then you can also play with the PC, PC as media center. My 10 year old CDs with DivX and all my DVDs I burned still play fine. next is burn it to flash, an also to a huge harddisk. That is why I have the 1TB Seagate external, most movies just a few keys away.
Of course not, but the rate doesn't have to be 20 times higher.
Again, how do you arrive at 20 times?
This part has to be a little more nifty than just a simple loop. Ideally there should be a characteriziation plus tempco-LUT so you can "steer" the PWM generator to the points where the signal wants it to, with little residual error.
Why not? The guys that designed the 1000W PMPO amp powered by a wall wart must have, at least on paper :-)
--
Regards, Joerg
http://www.analogconsultants.com/
"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
I have seen CDs and DVDs that have delaminated. The last (expensive) DVD we lost began to grow a blue cloud in the middle. It played to about half the movie, then cut out. Most probably last a long time but if they do delaminate it can happen within months. Tapes all lasted >10 years. Some are 20 years and still fine.
A PC in the living room? No way. SWMBO won't be happy about that. We have structured wiring so we could put it in the basement but then I'd have to design an RF remote that works in our RF-unfriendly house.
We don't watch many anyway. Maybe an old Humphrey Bogart, or a Western.
--
Regards, Joerg
http://www.analogconsultants.com/
"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
The ECLips range of digitally programmable delays might be what yoou had in mind. Most of them have an analog bandwidth of up to 1GHz, up to 1.5GHz for the faster ones.
The maximum programmable delays vary from something like 2nsec to to
10nsec, and you probably don't want to reprogram the delay while there is an edge propagating through the device. Putting a couple in parallel and combining the outputs isn't going to be an option - production tolerances are large, and the delays you get for a given digital input can vary quite a lot with temperature.
You were probably thinking of the MC10198
formatting link
which still seems to be being made, if not recommended for new production. Minimum output pulse width is 10nsec, which isn't entirely compatible with your 1GHz carrier frequency. It is a nice part, and it is reasonably easy to manipulate the monostable period - see figues 4 and 5 on the data sheet.
Actually, no. They would require me to digitize the signal first, which is what an FM scheme would avoid. Once it was digitized, I may as well just ship the data.
I build current-tuned diode laser gizmos from time to time, and they work great for many things. The main difficulty is that the output power as well as the optical frequency changes with the bias current, which constrains the available detection mechanisms. (Laser noise cancellers do amazing things at moderate speeds, but not in the gigahertz.)
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058
hobbs at electrooptical dot net
http://electrooptical.net
PWM is a kind of angular modulation. As such, it creates infinite sidebands on both sides of the carrier. Some part of the lower sideband inevitably falls into the bandwidth of the useful signal. How much of trash gets into the signal? It depends. Ballpark: for 60dB of rejection, the PWM carrier should be ~ x20 times of the highest signal frequency.
This could buy some accuracy. But, still loop cutoff ~ PWM rate/8. Or, if you want to really push phase margin, PWM rate/6. Consequently, the feedback is going to be quite shallow and it can't be the cure for all sins of PWM.
Not that I support this sort of audiofoolery, but there is a bit of sense there. For undistorted audio, there is generally no need for an audio amp to sustain power more then ~1/8 of the peak power.
Vladimir Vassilevsky DSP and Mixed Signal Design Consultant
Maybe. Having built more than a few in my audiophile lifetime, there's nothing like _real_ headroom. ...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
Obama isn't going to raise your taxes...it's Bush' fault: Not re-
newing the Bush tax cuts will increase the bottom tier rate by 50%
That's what was done in part of the paper that Jan referenced. Looks messy to me. I understand pure digital data fiber links, and I understand A/D and D/A conversion, and I sort of understand FM. Combining a fiber data link with a digital or FM modulation scheme compartmentalizes the problem into managable chunks. But all that optical stuff is out of my league.
Preferebly without digitizing. At our bare-minimum 100 MHz signal bandwidth, and 10 bits, sampling at 250 MHz, just past Nyquist, we'd be shipping 2.5 gbits/second. That's feasible, but I thought we'd consider FM too, which would be simpler to do.
We have a request from a customer to ship some wideband data over fiber. So we're thinking about it. It might turn into a standard product, too, especially if we make it accurate down to DC. Most fiber signal links are sort of ac-fuzzy... stick a signal in one end, get something sort of similar out the other.
The input signal needs to be band limited to 150 MHz, then sampled (but not quantized) at something above 300 MHz (Nyquist), then feed it to a comparator with a 300+ MHz linear ramp and the output drives the LD.
At receiver end, a sample&hold circuit is also required and a LPF.
Depending on how you are able to characterize the channel, different simulators may provide some useful data. Even with PSpice you might get sufficient info playing around with the different controlled sources available. If that is not sufficient, ADS will (almost) certainly give you whatever you want provided you invest sufficient time setting up the simulation (it is awful to use) and simulating.
Some of the delay lines have an analogue input fine tune,and the MC10198 allows you to modulate the pulse-width by an entirely anlogue route, but since the message I was trying to pass on was that the idea of 555 on steroids wasn't exactly realistic, what you've actually said is that you have missed the point.
On a sunny day (Tue, 13 Jul 2010 15:52:30 -0700) it happened Joerg wrote in :
You need the righ tones. Use Verbatim. I have 100 out of 100 correct. Some older ones Tdk for example, has some sort of funghus growing in the optical layer, even teh new ones, I returned boxes full, but the ones i already burned failed shortly after. In fact Verbatim is so remarkedly reliable that it amazes me. The other thing is: Use DVD+ ,as DVD+ allwos you to intrrupt the burning process (can appen, system load for example can cause that) and jus tcarry on. I can even stop burns with ctrlZ in Linux, to continue later... And finally, do not 'author' DVDs! If you are going to to play on the PC anyways , save the file as a binary image. In Linux it is so simple: To write a mpg file to disk as a binary image: growisofs -speed 3 -Z /dev/dvd=filename.mpg To verify it byte for byte: dvdimagecmp -a /dev/dvd -b filename.mpg If no errors then remove the original filename.mpg rm filename.mpg This only takes minutes, and can use all the 4 700 000 000 bytes on a DVD. Burn at a slow speed to get very good quality (3x in the above example), even if you burner can do much faster.
Then later to play it: xine /dev/dvd or, if you want to FFWD etc, copy to disk first: cp /dev/dvd filename.mpg xine filename.mpg
xine has all the needed playback features, language menu selection, even separate H and V zoom in case the aspect sucks.
Well, a PC these days can replace many boxes (PCI cards = TV receiver, video digitiser, audio, what not), and can be really small. Linux has a remote control project too. It can be smaller then the VCR :-)
Westerns? C4 and C5 transmits westerns several times a week here FTA on satellite (they are UK based). Was one monday with Burt Reynolds 'Hard Ground' (2003). Usually record it, next day I will look at it, if it sucks I delete it, if it is good I watch it, if it is execellent I burn a DVD. They are doing all the old Startrek movies from the eighties, with Kirk, last one was startrek_IV_the_voyage_home_1986. I went ot see it in the eigties, missed the start, was late in the theatre. So now I wanted to record it, it started, a huge thunderstorm appeared, signal went to zero for about
30 minutes, recorded the first few minues and the last part. So I still have not seen that part where Kirk is supposed to hijack his own ship
-he was made admiral before that-, but then degraded back to captain because of that in the end, after saving the worls of course. A great performance with late Scotty the engineer, where he invents 'transparent aluminum' on an old Mac :-) tries using the mouse as microhone for voce control ... Yes, TV can be fun.
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.