chrisz
Newbie level 1
in house designers versus outsourcing
I'm sorry for asking the group, (I'm sure you are all very busy) but I'm a lone engineer in Thailand on this project without anyone else to talk to.
I've been assigned a project requiring 2 distinct RF components and PCB antennas. I need an RFID chip at 13.56 MHz and an 802.15.4 (or equivalent) WPAN chip at 2.4 GHz.
Let me start by saying I haven't actually done any RF design since I left university 15 years ago, but I am a quick study. I am designing an industrial meter application that requires both of these interfaces. The sales figures call for up to a million of these units, so saving a penny makes a difference. Still, the engineering budget would make Ebenezer Scrooge proud, so I need to figure out how to do this in the most cost effective manner using the cheapest possible components, and, of course, it all needs to be finished yesterday.
(Aside: Did anyone else expect this was what real engineering was all about when you selected this as a career path?)
The basic dilemma I am faced with is the antenna design and resulting analog interface that goes with it. Both of the chips I am looking at (the TI 7960 for RFID and the Nordic Semiconductor nRF24L01 for the WPAN) come with reference designs that appear to be "good enough" for what I need to do.
I have a couple of questions though:
1. How important is the PCB manufacturing process in determining RF response at these frequencies? I understand it will have an effect, but does anyone have any real world experience with this? Is all FR4 created approximately equal? Remember, I need "good enough", not premium quality. (Certification could be a sticky issue though if the reference design doesn't pass.)
2. Next, I don't have a network analyzer. If it is likely Im going to need to adapt rather than copy the reference design, then I will need to get one. Probably about 300 kHz - 3 GHz to cover both bands, and preferably second hand given my meager budget. (Nobody will lease in Thailand.) Can anyone recommend a source that sells good quality equipment to disadvantaged engineers without a budget?
3. Assuming 2 is simply too expensive, another option is to make the PCB and then send the design out to have it characterized by someone else. Does anyone know of a commercial firm that can accept a sample PCB antenna and send me back a Smith Chart and characterization?
4. Final question. Given all of these restrictions, if you were me, how would you proceed? The complete modules I've looked at (even from the Taiwanese shops) are much too expensive, so I've ruled that out. Are the devices I've specified above a reasonable choice? The 1k budgetary costs are about $3 for the 7960, and about $2 for the nRFL01. Are there cheaper things out there that can do a similar job? Have I overlooked an obvious option?
Should I put my hope in a guy named Satish from one of the several freelancer websites who says he can do the whole job for me for $10 and have it ready a week ago?
For anyone who is experienced with this kind of work, how much engineering time would you estimate to get it done, and how much is a realistic budget for what I need to purchase? I have my own guess on the time, but I'd like to hear from a experienced RF hand.
I can't actually pay anyone for advice since I have no money, but if you help me out and have an occasion to come to Thailand I promise to buy you a beer.
Any information is appreciated.
Chris
I'm sorry for asking the group, (I'm sure you are all very busy) but I'm a lone engineer in Thailand on this project without anyone else to talk to.
I've been assigned a project requiring 2 distinct RF components and PCB antennas. I need an RFID chip at 13.56 MHz and an 802.15.4 (or equivalent) WPAN chip at 2.4 GHz.
Let me start by saying I haven't actually done any RF design since I left university 15 years ago, but I am a quick study. I am designing an industrial meter application that requires both of these interfaces. The sales figures call for up to a million of these units, so saving a penny makes a difference. Still, the engineering budget would make Ebenezer Scrooge proud, so I need to figure out how to do this in the most cost effective manner using the cheapest possible components, and, of course, it all needs to be finished yesterday.
(Aside: Did anyone else expect this was what real engineering was all about when you selected this as a career path?)
The basic dilemma I am faced with is the antenna design and resulting analog interface that goes with it. Both of the chips I am looking at (the TI 7960 for RFID and the Nordic Semiconductor nRF24L01 for the WPAN) come with reference designs that appear to be "good enough" for what I need to do.
I have a couple of questions though:
1. How important is the PCB manufacturing process in determining RF response at these frequencies? I understand it will have an effect, but does anyone have any real world experience with this? Is all FR4 created approximately equal? Remember, I need "good enough", not premium quality. (Certification could be a sticky issue though if the reference design doesn't pass.)
2. Next, I don't have a network analyzer. If it is likely Im going to need to adapt rather than copy the reference design, then I will need to get one. Probably about 300 kHz - 3 GHz to cover both bands, and preferably second hand given my meager budget. (Nobody will lease in Thailand.) Can anyone recommend a source that sells good quality equipment to disadvantaged engineers without a budget?
3. Assuming 2 is simply too expensive, another option is to make the PCB and then send the design out to have it characterized by someone else. Does anyone know of a commercial firm that can accept a sample PCB antenna and send me back a Smith Chart and characterization?
4. Final question. Given all of these restrictions, if you were me, how would you proceed? The complete modules I've looked at (even from the Taiwanese shops) are much too expensive, so I've ruled that out. Are the devices I've specified above a reasonable choice? The 1k budgetary costs are about $3 for the 7960, and about $2 for the nRFL01. Are there cheaper things out there that can do a similar job? Have I overlooked an obvious option?
Should I put my hope in a guy named Satish from one of the several freelancer websites who says he can do the whole job for me for $10 and have it ready a week ago?
For anyone who is experienced with this kind of work, how much engineering time would you estimate to get it done, and how much is a realistic budget for what I need to purchase? I have my own guess on the time, but I'd like to hear from a experienced RF hand.
I can't actually pay anyone for advice since I have no money, but if you help me out and have an occasion to come to Thailand I promise to buy you a beer.
Any information is appreciated.
Chris