Software radio receiver system

embarrassedlopsidedAI and Robotics

Nov 14, 2013 (3 years and 8 months ago)

68 views

Biosensors


Equipment requested:

Software radio receiver system

Pentek, Inc.,

One Park Way

Upper Saddle River, NJ 07458

www.pentek.com


System components:

Model

Description

Price

4205
-
006
-
057

VIM/PMC Carrier, 1 GHz, Fibre ch

$9,745

6236

14
-
bit A/D & FPG
A+OPT DR VIM
-
2

$7,495

4999S

READYFLOW 1 yr subscription

$2,500

8204

CARD CAGE: 7SL 500W 2 Fan port

$2,595

8215
-
064

Configuration services

$2,630

8332
-
207
-
507

2 Disc 2Gbit 70GB JBOD W/1 YR

$2,935





TOTAL

$27,900



Functionality:

This system will pr
ovide a software
-
defined radio receiver (SDR) operating at approximately
65MHz, which can be used for acquisition of wireless digital data from a wireless biological
sensor network (WBSN). The WBSN will consist of wireless sensors embedded in living tissu
e
samples (e.g., rabbit heart) for the purpose of recording electrical and mechanical activity. For
some proposed studies, there will be more than 500 sensors operating simultaneously. The data
from these sensors will be aggregated through several hierarc
hical levels into approximately 8
channels of high speed digital data, which will transmitted wirelessly to a receiver/decoder/data
-
logger system. The use of the requested SDR equipment will allow extreme flexibility in the
design of the sensors and trans
mitters. The latter are subject to severe constraints on size and
power, and therefore cannot be designed to use optimal encoding or RF protocols. However,
these shortcomings on the transmitter side can be largely compensated for by using an SDR
receiver w
ith its potential for adaptive parameter adjustment and high dynamic range.


Details of the Research Using Wireless Biological Sensor Networks:


Background and Motivation

The acquisition and telemetry of biomedical data obtained in vivo requires attention
to issues of
power, size, data rate, and biocompatibility. The present methods can be characterized by the
means used to provide circuit power and to transmit data. Various methods used for providing
electrical power include inductor loop coupling [1, 2],

battery or supercapacitor [3], and
photovoltaics [3]. Data transmission is typically achieved using inductive coupling [1, 2],
infrared optical links [3, 4, 5], and absorption modulation (resonance shift) [6].


Review of the literature shows that the sys
tems demonstrated thus far are designed to transmit
relatively low data rates, in the range from 10 to 100 samples per second, with resolutions
ranging from 6 to 14 bits per sample. Under these conditions, inductive coupling in the range of
27 to 40 MHz c
an be used effectively to provide telemetry and to supply power transcutaneously
to the bioelectronics. One drawback of this method is the degradation of signal to noise ratio to
the relatively large electromagnetic fields involved. An alternative is prov
ided by using near
-
infrared photovoltaics. Systems using laser diodes, LED’s, photovoltaic cells, and photodiodes
operating in the range from 810 to 890 nm have been demonstrated. Transmission of digital data
through human tissue with thickness up to 25 m
m has been shown to be feasible.


For the work proposed herein, the primary novelty is the requirement for data rates very much
higher than heretofore reported. In support of the proposed cardiology studies, it is proposed to
transmit up to 528 channels o
f data at a rate of 2,000 samples per second, with 16
-
bit resolution.
The resulting data rate is 16 Mbits/second. An additional consideration is the somewhat longer
distance the signals must propagate in tissue and biofluids. Existing systems are designe
d for
transmitting from just under the skin to just outside the skin, whereas the proposed system must
be designed to transmit through as much as several centimeters of highly conductive biomatter.


Technical Approach

The technical approach for data acqu
isition and telemetry, staged over five years, is aimed at
developing a comprehensive solution to the issues of high data rate transmission, small size, and
low power. The schematic for a single probe telemetry system is shown in Figure 1. This
drawing s
hows the concept for a probe incorporating multiple electrode contacts for resolving
electrical activity as a function of depth. The assembly consists of a rigid substrate to which the
probe is attached, and a silicon integrated circuit with CMOS electron
ics. The circuitry consists
of an analog multiplexer, analog
-
to
-
digital converter, data encoding, RF transmission electronics,
and a plated spiral antenna.


Figure 2 shows a concept for a two
-
dimensional array of probes with associated
microelectronics. I
n this case, the entire assembly is designed to be inserted as a unit. The
electronics detail is similar to that described in Fig. 1, however signal routing is a more severe
challenge to be studied as a part of the proposed research effort.


The initial ap
proach will be to use digital spread spectrum (DSS) RF circuitry operating at 2.45
GHz. Components are already developed for RF telephony and computer wireless modems, and
are widely available and well characterized. This frequency range offers sufficient
bandwidth for
the anticipated data rates, and RF power coupling efficiency can be relatively high even with the
small antennas to be used. A reasonable concern arises as to the absorption characteristics of
biological tissue at this frequency, but prelimin
ary studies have shown that digital information
can be transmitted with negligible error through several centimeters of tissue using DSS
components operating at a few milliwatts of RF power.


Initial design will focus on using inductively coupled power s
upplied to the electronics, using
either the same antenna used data telemetry , or possibly a separate antenna specifically designed
for that purpose.


In one scheme considered, probe arrays may be networked to a master telemetry module to
reduce the RF po
wer and computational load borne by each array. In this case, all digital data
will be routed through the master module for transmission to the external receiver.


The research schedule for the RF telemetry component of the proposed five
-
year project is
ou
tlined in the following paragraphs.


Year 1



Define radio frequency link characteristics (especially power, bandwidth, and antenna size)



Design amplifiers and multiplexer for on
-
chip implementation.



Test data compression algorithms


Year 2



Fabricate sensors

with on
-
board electronics



Begin design of digital circuits (analog
-
to
-
digital converter, digital multiplexer,
programmable logic arrays)



Transfer temporal data compression algorithms to chips



Develop RF link prototype


Year 3



Implement data compression al
gorithms capability on sensors



Implement inter
-
chip communication with RF links (networking)


Year 4



Implement signal processing algorithms on
-
chip



Investigate spatial data compression



Design automatic sensor localization technique


Year 5



Implement comple
te RF network between sensor arrays and external receiver



Implement spatial data compression using full RF network between sensor arrays



Demonstrate acquisition of up to 528 parallel channels of data at 2kHz sample rate, with 16
bits/sample.





References

1. Renard S., Pisella C., Collet J., Perruchot F., Kergueris C.. Destrez Ph., Rey P., Delorme N.,
Dallard E. Miniature pressure acquisition microsystem for wireless in vivo measurements.

1
st

Annual International IEEE
-
EMBS Special Topic Conference on Mic
rotechnologies in Medicine
and Biology
, Oct. 12
-
14, 2000, Lyon, France.


2. Mokwa W., Schnakenberg U., Implantable microdevices.
Eurosensors XII
I, 1999; 741
-
746.


3. Murakwa K., Kobayashi M., Nakamura O., Kawata S., A wireless near
-
infrared energy system

for medical implants.
IEEE Engineering in Medicine and Biology
, 1999; November/December,
70
-
72.


4. Mussivand T., Hum A., Holmes K. S., Keon W. J. Wireless monitoring and control for
implantable rotary blood pumps.
Artificial Organs

1997; 21(7):661
-
664.


5. Mussivand T., Hendry P. J., Masters R. G., Holmes K. S., Hum A., Keon W. J. A remotely
controlled and powered artificial heart pump.
Artificial Organs

1996; 20(12)1314
-
1319.


6. Huang Q., Oberle M. A 0.5
-
mW passive telemetry IC for biomedical appli
cations.
IEEE J.
Solid State Circuits

1998; 33(7): 937
-
946.



Insertion
Probe

Electrode

Contact

RF Planar Antenna

Rigid
Substrate

Encapsulation

Silicon CMOS
Integrated Circuit or
Multi
-
chip Module

Figure 1. Schematic of a single
-
probe telemetry system. The probe is attached to a rigid substrate which
incorporates the signal processing,

RF electronics, and a planar antenna. For clarity of drawing, the aspect ratio of
the probe is highly distorted. Anticipated dimensions of the probe are approximately 2 cm long and 100

m wide.




Two
-
dimensional Probe
Array

Rigid Substrate

Electronics a
nd
Telemetry Assembly

Figure 2. Conceptual layout of a telemetry system for a two dimensional probe array.

Wireless Computing and Networking Infrastructure Equipment


Equipment requested:

Wireless Sensor Networking System


Crossbow Technology, Inc.

41 Daggett Dr.

San Jose, CA 95134

www.xbow.c
om


Model

Description

Price

MOTE
-
KIT5040CB

WIRELESS SNSR
NETWORK KIT 900MHz

$1,995

SP
-
KIT420

SENSICAST EVALUATION
SOFTWARE

$195

MIB600CA

SP
-
KIT420 STARGATE
ADVANCED KIT

$995

MPR500CA

Ethernet Interface Board

$349


MICA2DOT 900 MHz Radio
Modules (10)

$1,150





TOTAL

$4,684



Functionality

The requested system will be used in our cooperative robotics research thrust. The remote
wireless nodes will be installed on both mobile and stationary robots. The equipment system will
provide communication, sen
sor interface, and network monitoring capability for a cooperative
robotics testbed.


Research plan

Figure 1 below illustrates a human and robotic cooperative testbed designed for space
applications, in which significant time delays may be present. Initial
ly, the communications
infrastructure will be provided exclusively by the MICA Mote equipment requested in this
proposal. Our goal is to develop a simultaneous capability to perform the networking
communications using software
-
defined radio (SDR) of our ow
n design. At that point, the MICA
Mote system will transition to a role of network monitoring and communications backup.



In this project, we will investigate the ability of software
-
defined radio (SDR) to provide
co
m
munication for a heterogeneous colony
of laboratory
-
based cooperative robots operating in a
sim
u
lated interplanetary exploration environment. Communication latency will be introduced
artif
i
cially to mimic time delays consistent with interplanetary missions. Members of the colony
will use a v
a
r
iety of communication modes in order to simulate a realistic set of scenarios useful
for space exploration.





We shall implement a software module that can reside on each node (human or robot) to enable
cooperative behavior. This is intended to be gener
al in nature to enable the implementation of a
wide variety of interesting scenarios. Example scenario: Human operator desires to teleoperate
robot R1, but cannot connect. Robot R2, located nearer to R1, is equipped with SDR that can
"forward messages" ba
ck and forth under software control. There are time delays TD1 from
human to R1 and TD2 between R1 and R2.


Initially, using existing code as much as possible, we shall implement software modules to
facilitate co
-
operative behavior and support high level h
uman commands. Modules will reside
on every human and robot centered node. Where appropriate these modules will support human
robot interaction through graphical user interfaces. Initially the modules will support
teleoperation of the robot by a remote
human user.


After demonstrating feasibility, we shall develop a software environment with sufficient
flexibility to allow a variety of cooperation scenarios to be investigated. These may include
"virtual presence" applications, collabora
-
tive assembly o
f structures, and coordinated sensing
with heterogeneous robot sensor platforms, among others. Additionally, as mentioned in the
Figure 1. Illustration of the proposed seven
-
node human/robotic colony in
which cooperative behavior is enabled by software
-
defined radio (SDR)
a
t
tached to each network node. The nodes ma
y be physically widely
distributed as modeled by time delay
TDn

injected into the network. The
values of
TD

may vary widely across the network to simulate physical
separations ranging from interplanetary to proximal.

STATIONARY

ROBOT

STATIONARY

ROBOT

COMMUNICATION

NETWORK

SDR

MOBILE

ROB
OT

MOBILE

ROBOT

HUMAN

INTERFACE

PC

HUMAN

INTERFACE

SDR

PC

MOBILE

ROBOT

SDR

SDR

SDR

SDR

SDR

TD1

TD2

TD3

TD4

TD5

TD6

TD7

Phase 1 description, we will add some ability for the robot to act with limited autonomy, yet
remain under the supervision of
a remote human user. This mode, often called teleassistance, is
very practical in the presence of large communication delays. Such delays can make direct
teleoperation very difficult and frustrating for the user. Giving the robot limited autonomy to
per
form basic simple tasks enables the user to direct the actions of the robot in terms of these
simple tasks. This type of problem decomposition is more robust in the presence of
communication delays.


References

(to be provided )